Lennox G61MPV-36C-090, G61MPV-36B-070, G61MPV-36B-071, G61MPV-60C-091, G61MPV-60C-110 Installation Instructions Manual

Page 1

01/11

*2P0111*

506506−01

*P506506-01*

E 2011 Lennox Industries Inc.

Dallas, Texas, USA

THIS MANUAL MUST BE LEFT WITH THE

HOMEOWNER FOR FUTURE REFERENCE

INSTALLATION
INSTRUCTIONS

G61MPV SERIES UNITS

GAS UNITS

506506−01
01/2011

Supersedes 07/2010

Table of Contents

Unit Dimensions 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

G61MPV Parts Arrangement 3. . . . . . . . . . . . . . . . . . . . .

Shipping and Packing List 4. . . . . . . . . . . . . . . . . . . . . . .

Safety Information 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Use of Furnace as Construction Heater 5. . . . . . . . . . .

General 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Combustion, Dilution & Ventilation Air 6. . . . . . . . . . . . .

Installation − Setting Equipment 9. . . . . . . . . . . . . . . . . .

Filters 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Duct System 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Pipe & Fittings Specifications 16. . . . . . . . . . . . . . . . . . .

Vent Piping Guidelines 19. . . . . . . . . . . . . . . . . . . . . . . . .

Joint Cementing Procedure 20. . . . . . . . . . . . . . . . . . . . .

Venting Practices 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Gas Piping 36. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Electrical 38. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Integrated Control Board 45. . . . . . . . . . . . . . . . . . . . . . .

Unit Start−Up 55. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Gas Pressure Adjustment 56. . . . . . . . . . . . . . . . . . . . . .

High Altitude Information 57. . . . . . . . . . . . . . . . . . . . . . .

Other Unit Adjustments 59. . . . . . . . . . . . . . . . . . . . . . . .

Service 60. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Ignition Control Board Diagnostic Codes 63. . . . . . . . .

Troubleshooting 64. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Repair Parts List 69. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Vent Pipe Sizing Worksheet 70. . . . . . . . . . . . . . . . . . . .

Start−Up & Performance Check List 71. . . . . . . . . . . . . .

WHAT TO DO IF YOU SMELL GAS:

Do not store or use gasoline or other
flammable vapors and liquids in the
vicinity of this or any other ap­pliance.

Installation and service must be
performed by a qualified installer,
service agency or the gas supplier.

D Do not try to light any appliance.
D Do not touch any electrical switch; do not

use any phone in your building.

D Immediately call your gas supplier from a

neighbor’s phone. Follow the gas supplier’s
instructions.

D If you cannot reach your gas supplier, call

the fire department.

FIRE OR EXPLOSION HAZARD.

Failure to follow safety warnings exact­ly could result in serious injury, death,
or property damage.

WARNING

D Leave the building immediately.

Litho U.S.A.

Page 2

G61MPV Unit Dimensions − inches (mm)

*Bottom Return

Air Opening

*Bottom Return

Air Opening

ELECTRICAL INLET

(Either Side)

SUPPLY AIR

OPENING

AIR FLOW

FRONT VIEW SIDE VIEW

TOP VIEW

A

B 9/16 (14)

C

3/4 (19)

3/4 (19)

28−1/2

(724)

19−7/16

(494)

23−1/2

(597)
4−1/4
(108)

11−5/8 (295)

Right

9−3/4 (248)

Left

4−7/8 (124) Right

2−1/4 (57) Left

40

(1016)

4

(102)

1−15/16 (49)

23

(584)

14**

(356)

9/16

(14)

16

(406)

14−3/4

(375)

5/8 (16)

23-3/4 (603)

25 (635)

GAS PIPING INLET

(Either Side)

EXHAUST AIR OUTLET

(Either Side)

CONDENSATE

TRAP CONNECTION

(Either Side)

2−1/2

(64)

18-3/4 (476)

1

OPTIONAL

EXTERNAL

SIDE RETURN

AIR FILTER KIT

(Either Side)

1

OPTIONAL

EXTERNAL

SIDE RETURN

AIR FILTER KIT

(Either Side)

*OPTIONAL

RETURN CUTOUT

(Either Side)

1

Optional External Side Return Air Filter Kit is not for use

with the optional RAB Return Air Base.

*60C and 60D size units installed in upflow applications
that require air volumes over 1800 cfm (850 L/s) must have
one of the following:

1. Single side return air with transition, to accommodate
20 x 25 x 1 in. (508 x 635 x 25 mm) air filter.
Required to maintain proper air velocity.

2. Single side return air with optional RAB Return Air Base

3. Bottom return air.

4. Return air from both sides.

5. Bottom and

one side return air.

Refer to Engineering Handbook for additional information.

**Consider sizing requirements for optional IAQ equip­ment before cutting side return opening.

COMBUSTION AIR INTAKE

(Either Side)

6−1/2
(165)

4−1/8
(103)

6−1/2
(165)

6−3/4
(171)

5−1/2
(140)

3−1/8

(79)

Model No.

A B C

in. mm in. mm in. mm

G61MPV−36B−045
G61MPV−36B−070
G61MPV−36B−071

17−1/2 446 16−3/8 416 16 406

G61MPV−36C−090
G61MPV−60C−090
G61MPV−60C−091
G61MPV−60C−110
G61MPV−60C−111

21 533 19−7/8 505 19−1/2 495

G61MPV−60D−135 24−1/2 622 23−3/8 546 23 584

Page 3

G61MPV Parts Arrangement

FIGURE 1

TOP CAP

CABINET

BURNER BOX

ASSEMBLY

SIGHT

GLASS

DuralokPlus

TM

HEAT EXCHANGER

ASSEMBLY

CONDENSER COIL

DOOR

INTERLOCK

SWITCH

COLD HEADER

(COLLECTOR)

BOX

COMBUSTION AIR

INDUCER

BLOWER

ACCESS

PANEL

BURNER
ACCESS

PANEL

FLUE

COLLAR

COMBUSTION

AIR PRESSURE

PROVE SWITCHES*

PRIMARY LIMIT

WARM HEADER

(COLLECTOR)

BOX

GAS VALVE

AND MANIFOLD

SECONDARY

LIMITS (2)

POWER CHOKE

(5 Ton Only)

BLOWER MOTOR

TRANSFORMER

*G61MPV−36B−045

units are equipped

with two switches.

Two−Stage, Variable Speed

Integrated Control

CIRCUIT

BREAKER

Page 4

G61MPV Gas Furnace

The G61MPV category IV gas furnace is equipped with a
two−stage, variable speed integrated control. This control
ensures compatibility with Lennox’ Harmony III zone con­trol system, as well as a thermostat which provides humid­ity control. Each G61MPV is shipped ready for installation
in the upflow, downflow, horizontal left air discharge or
horizontal right air discharge position. The furnace is
shipped with the bottom panel in place. The bottom panel
must be removed if the unit is to be installed in upflow ap­plications with bottom return air. The bottom panel must
also be removed and discarded in all downflow or horizon­tal applications.

The furnace is equipped for installation in natural gas ap­plications. A conversion kit (ordered separately) is re­quired for use in propane/LP gas applications.

The G61MPV can be installed as either a Direct Vent or a
Non−Direct Vent gas central furnace.

NOTE − In Direct Vent installations, combustion air is taken
from outdoors and flue gases are discharged outdoors. In
Non−Direct Vent installations, combustion air is taken from
indoors and flue gases are discharged outdoors. See figure
2 for applications involving roof termination.

FIGURE 2

DIRECT VENT INSTALLATION NON−DIRECT VENT

INSTALLATION

EXHAUST
OUTLET

COMBUSTION
AIR INTAKE
OUTSIDE OF
HOUSE

CONDENSATE

DRAIN

EXHAUST
OUTLET

G61MPV

COMBUSTION

AIR INTAKE INSIDE

OF HOUSE

G61MPV

CONDENSATE

DRAIN

Shipping and Packing List

Package 1 of 1 contains

1 − Assembled G61MPV unit
1 − Bag assembly containing the following:

3 − Screws
3 − Wire nuts
1 − Snap bushing
1 − Snap plug
1 − Wire tie
1 − Condensate trap
1 − Condensate trap cap
2 − 2" diameter vent / intake plugs

1 − 3" diameter cabinet plug (intake)
1 − 2" diameter debris screen
1 − Logo sticker (for use in downflow applications)

NOTE − G61MPV−60C−110 and G61MPV−60C−111 units
also include a 2" diameter PVC street elbow, which is
shipped on the blower deck in the heating compartment.
G61MPV−60D−135 units are shipped with a 3" to 2" PVC
reducing elbow.

Canadian Installations Only − Replace the provided 2"
street elbow shipped with the G61MPV−60C−110 and
G61MPV−60C−111 units with 2" street elbow Y0162. Re­place the provided 3" X 2" reducing elbow shipped with the
G61MPV−60D−135 units with 3" X 2" reducing elbow
40W22. Y0162 and 40W22 meet B149 vent requirements.

The following items may also be ordered separately:
1 − Thermostat
1 − Propane/LP changeover kit

DANGER

Danger of explosion.

There are circumstances in which odorant used with
LP/propane gas can lose its scent. In case of a leak,
LP/propane gas will settle close to the floor and may
be difficult to smell. An LP/propane leak detector
should be installed in all LP applications.

Check equipment for shipping damage. If you find any
damage, immediately contact the last carrier.

Safety Information

WARNING

Improper installation, adjustment, alteration, service
or maintenance can cause property damage, person­al injury or loss of life. Installation and service must
be performed by a licensed professional installer (or
equivalent), service agency or the gas supplier.

CAUTION

As with any mechanical equipment, personal injury
can result from contact with sharp sheet metal
edges. Be careful when you handle this equipment.

Use only the type of gas approved for use with this furnace.
Refer to unit nameplate.

G61MPV units are CSA International certified to ANSI
Z21.47 and CSA 2.3 standards.

In the USA, installation of gas furnaces must conform with lo­cal building codes. In the absence of local codes, units must
be installed according to the current National Fuel Gas Code
(ANSI-Z223.1/NFPA 54). The National Fuel Gas Code is
available from the following address:

Page 5

American National Standards Institute, Inc.
11 West 42nd Street
New York, NY 10036

In Canada, installation must conform with current National
Standard of Canada CSA-B149 Natural Gas and Propane
Installation Codes, local plumbing or waste water codes
and other applicable local codes.

In order to ensure proper unit operation in non−direct vent
applications, combustion and ventilation air supply must be
provided according to the current National Fuel Gas Code
or CSA-B149 standard.

This furnace is CSA International certified for installation
clearances to combustible material as listed on the unit
nameplate and in the tables in figures 8, 13 and 17. Acces­sibility and service clearances must take precedence over fire
protection clearances.

NOTE − For installation on combustible floors, the furnace
shall not be installed directly on carpeting, tile, or other
combustible material other than wood flooring.

For installation in a residential garage, the furnace must
be installed so that the burner(s) and the ignition source
are located no less than 18 inches (457 mm) above the
floor. The furnace must be located or protected to avoid
physical damage by vehicles. When a furnace is installed
in a public garage, hangar, or other building that has a haz­ardous atmosphere, the furnace must be installed accord­ing to recommended good practice requirements and cur­rent National Fuel Gas Code or CSA B149 standard.

NOTE − Furnace must be adjusted to obtain a temperature
rise within the range specified on the unit nameplate. Failure
to do so may cause erratic limit operation.

This G61MPV furnace may be used as a high−static unit
heater. The G61MPV may also be installed in an aircraft
hangar in accordance with the Standard for Aircraft Han­gars (ANSI/NFPA No. 408−1990).

Installation in parking structures must be in accordance
with the Standard for Parking Structures (ANSI/NFPA No.
88A−1991). Installation in repair garages must be in accor­dance with the Standard for Repair Garages (ANSI/NFPA
No. 88B−1991).

This G61MPV furnace must be installed so that its electri­cal components are protected from water.

When this furnace is used with cooling units, it shall be
installed in parallel with, or on the upstream side of, cooling
units to avoid condensation in the heating compartment.
With a parallel flow arrangement, a damper (or other means
to control the flow of air) must adequately prevent chilled air

from entering the furnace. If the damper is manually oper­ated, it must be equipped to prevent operation of either the
heating or the cooling unit, unless it is in the full HEAT or
COOL setting.

When installed, this furnace must be electrically grounded
according to local codes. In addition, in the United States,
installation must conform with the current National Electric
Code, ANSI/NFPA No. 70. The National Electric Code
(ANSI/NFPA No. 70) is available from the following ad­dress:

National Fire Protection Association
1 Battery March Park
Quincy, MA 02269

In Canada, all electrical wiring and grounding for the unit
must be installed according to the current regulations of the
Canadian Electrical Code Part I (CSA Standard C22.1)
and/or local codes.

NOTE − This furnace is designed for a minimum continu­ous return air temperature of 60°F (16°C) or an intermit­tent operation down to 55°F (13°C) dry bulb for cases
where a night setback thermostat is used. Return air tem­perature must not exceed 85°F (29°C) dry bulb.

The G61MPV furnace may be installed in alcoves, closets,
attics, basements, garages, and utility rooms.

This furnace design has not been CSA certified for installa­tion in mobile homes, recreational vehicles, or outdoors.

Never use an open flame to test for gas leaks. Check all
connections using a commercially available soap solution
made specifically for leak detection.

Use of Furnace as Construction Heater

Lennox does not recommend the use of G61MPV units as
a construction heater during any phase of construction.
Very low return air temperatures, harmful vapors and op­eration of the unit with clogged or misplaced filters will dam­age the unit.

G61MPV units may be used for heating of buildings or
structures under construction, if the following conditions
are met:

D The vent system must be permanently installed per

these installation instructions.

D A room thermostat must control the furnace. The use of

fixed jumpers that will provide continuous heating is not
allowed.

D The return air duct must be provided and sealed to the

furnace.

D Return air temperature range between 60°F (16°C) and

80°F (27°C) must be maintained.

D Air filters must be installed in the system and must be

maintained during construction.

D Air filters must be replaced upon construction comple-

tion.

Page 6

D The input rate and temperature rise must be set per the

furnace rating plate.

D One hundred percent (100%) outdoor air must be pro-

vided for combustion air requirements during construc­tion. Temporary ducting may supply outdoor air to the
furnace. Do not connect duct directly to the furnace.
Size the temporary duct following these instructions in
section for Combustion, Dilution and Ventilation Air in a
confined space with air from outside.

D The furnace heat exchanger, components, duct system,

air filters and evaporator coils must be thoroughly
cleaned following final construction clean−up.

D All furnace operating conditions (including ignition, in-

put rate, temperature rise and venting) must be verified
according to these installation instructions.

General

These instructions are intended as a general guide and do
not supersede local codes in any way. Consult authorities
having jurisdiction before installation.

In addition to the requirements outlined previously, the fol­lowing general recommendations must be considered
when installing a G61MPV furnace:

• Place the furnace as close to the center of the air dis­tribution system as possible. The furnace should also be
located close to the chimney or vent termination point.

• When the furnace is installed in non−direct vent applica­tions, do not install the furnace where drafts might blow
directly into it. This could cause improper combustion
and unsafe operation.

• When the furnace is installed in non−direct vent applica­tions, do not block the furnace combustion air opening
with clothing, boxes, doors, etc. Air is needed for proper
combustion and safe unit operation.

• When the furnace is installed in an attic or other insu­lated space, keep insulation away from the furnace.

• When the furnace is installed in an unconditioned
space, consider provisions required to prevent freezing
of condensate drain system.

CAUTION

G61MPV unit should not be installed in areas normal­ly subject to freezing temperatures.

WARNING

Product contains fiberglass wool.

Disturbing the insulation in this product during
installation, maintenance, or repair will expose you
to fiberglass wool. Breathing this may cause lung
cancer. (Fiberglass wool is known to the State of Cal­ifornia to cause cancer.)

Fiberglass wool may also cause respiratory, skin,
and eye irritation.

To reduce exposure to this substance or for further
information, consult material safety data sheets
available from address shown below, or contact your
supervisor.

Lennox Industries Inc.
P.O. Box 799900
Dallas, TX 75379−9900

Combustion, Dilution & Ventilation Air

If the G61MPV is installed as a Non−Direct Vent Fur­nace, follow the guidelines in this section.

NOTE − In Non−Direct Vent installations, combustion air
is taken from indoors and flue gases are discharged out−
doors.

WARNING

Insufficient combustion air can cause headaches,
nausea, dizziness or asphyxiation. It will also cause
excess water in the heat exchanger resulting in rust­ing and premature heat exchanger failure. Excessive
exposure to contaminated combustion air will result
in safety and performance related problems. Avoid
exposure to the following substances in the com­bustion air supply:

Permanent wave solutions
Chlorinated waxes and cleaners
Chlorine base swimming pool chemicals
Water softening chemicals
De−icing salts or chemicals
Carbon tetrachloride
Halogen type refrigerants
Cleaning solvents (such as perchloroethylene)
Printing inks, paint removers, varnishes, etc.
Hydrochloric acid
Cements and glues
Antistatic fabric softeners for clothes dryers
Masonry acid washing materials

In the past, there was no problem in bringing in sufficient
outdoor air for combustion. Infiltration provided all the air
that was needed. In today’s homes, tight construction
practices make it necessary to bring in air from outside
for combustion. Take into account that exhaust fans, ap­pliance vents, chimneys, and fireplaces force additional

Page 7

air that could be used for combustion out of the house.
Unless outside air is brought into the house for combus­tion, negative pressure (outside pressure is greater than
inside pressure) will build to the point that a downdraft
can occur in the furnace vent pipe or chimney. As a result,
combustion gases enter the living space creating a po­tentially dangerous situation.

In the absence of local codes concerning air for combus−
tion and ventilation, use the guidelines and procedures in
this section to install G61MPV furnaces to ensure effi­cient and safe operation. You must consider combustion
air needs and requirements for exhaust vents and gas
piping. A portion of this information has been reprinted
with permission from the National Fuel Gas Code (ANSI−
Z223.1/NFPA 54). This reprinted material is not the com­plete and official position of the ANSI on the referenced
subject, which is represented only by the standard in its
entirety.

In Canada, refer to the standard CSA B149 installation
codes.

CAUTION

Do not install the furnace in a corrosive or contami­nated atmosphere. Meet all combustion and ventila­tion air requirements, as well as all local codes.

All gas-fired appliances require air for the combustion pro­cess. If sufficient combustion air is not available, the fur­nace or other appliance will operate inefficiently and un­safely. Enough air must be provided to meet the needs of all
fuel−burning appliances and appliances such as exhaust
fans which force air out of the house. When fireplaces, ex­haust fans, or clothes dryers are used at the same time as
the furnace, much more air is required to ensure proper
combustion and to prevent a downdraft. Insufficient air
causes incomplete combustion which can result in carbon
monoxide.

In addition to providing combustion air, fresh outdoor air di­lutes contaminants in the indoor air. These contaminants
may include bleaches, adhesives, detergents, solvents
and other contaminants which can corrode furnace compo­nents.

The requirements for providing air for combustion and ven­tilation depend largely on whether the furnace is installed in
an unconfined or a confined space.

Unconfined Space

An unconfined space is an area such as a basement or
large equipment room with a volume greater than 50 cubic
feet (1.42 m

3

) per 1,000 Btu (.29 kW) per hour of the com­bined input rating of all appliances installed in that space.
This space also includes adjacent rooms which are not

separated by a door. Though an area may appear to be un­confined, it might be necessary to bring in outdoor air for
combustion if the structure does not provide enough air by
infiltration. If the furnace is located in a building of tight
construction with weather stripping and caulking around
the windows and doors, follow the procedures in the air
from outside section.

Confined Space

A confined space is an area with a volume less than 50 cubic
feet (1.42 m

3

) per 1,000 Btu (.29 kW) per hour of the com−
bined input rating of all appliances installed in that space. This
definition includes furnace closets or small equipment rooms.

When the furnace is installed so that supply ducts carry air
circulated by the furnace to areas outside the space con­taining the furnace, the return air must be handled by ducts
which are sealed to the furnace casing and which terminate
outside the space containing the furnace. This is especially
important when the furnace is mounted on a platform in a
confined space such as a closet or small equipment room.
Even a small leak around the base of the unit at the platform
or at the return air duct connection can cause a potentially
dangerous negative pressure condition. Air for combustion
and ventilation can be brought into the confined space ei­ther from inside the building or from outside.

Air from Inside

If the confined space that houses the furnace adjoins a
space categorized as unconfined, air can be brought in by
providing two permanent openings between the two
spaces. Each opening must have a minimum free area of 1
square inch (645 mm

2

) per 1,000 Btu (.29 kW) per hour of
total input rating of all gas−fired equipment in the confined
space. Each opening must be at least 100 square inches
(64516 mm

2

). One opening shall be within 12 inches (305
mm) of the top of the enclosure and one opening within 12
inches (305 mm) of the bottom. See figure 3.

FIGURE 3

EQUIPMENT IN CONFINED SPACE − ALL AIR FROM INSIDE

OPENINGS

(To Adjacent

Unconfined

Space)

NOTE − Each opening shall have a free area of at least one square
inch per 1,000 Btu (645mm

2

per .29kW) per hour of the total input

rating of all equipment in the enclosure, but not less than 100 square
inches (64516mm.

2).

G61MPV

ROOF TERMINATED

EXHAUST PIPE

SIDE WALL

TERMINATED EX-

HAUST PIPE (ALTER-

NATE LOCATION)

Page 8

Air from Outside

If air from outside is brought in for combustion and ventila­tion, the confined space shall be provided with two perma­nent openings. One opening shall be within 12" (305mm)
of the top of the enclosure and one within 12" (305mm) of
the bottom. These openings must communicate directly
or by ducts with the outdoors or spaces (crawl or attic) that
freely communicate with the outdoors or indirectly
through vertical ducts. Each opening shall have a mini­mum free area of 1 square inch per 4,000 Btu (645mm

2

per 1.17kW) per hour of total input rating of all equipment
in the enclosure. When communicating with the outdoors
through horizontal ducts, each opening shall have a mini­mum free area of 1 square inch per 2,000 Btu (645mm

2

per .59kW) per total input rating of all equipment in the en­closure (See figure 4).

FIGURE 4

EQUIPMENT IN CONFINED SPACE − ALL AIR FROM OUTSIDE

(Inlet Air from Crawl Space and Outlet Air to Ventilated Attic)

NOTE−The inlet and outlet air openings shall each have a free area
of at least one square inch per 4,000 Btu (645mm

2

per 1.17kW) per

hour of the total input rating of all equipment in the enclosure.

OUTLET

AIR

INLET

AIR

VENTILATION

LOUVERS

(For unheated

crawl space)

G61MPV

ROOF TERMINATED

EXHAUST PIPE

VENTILATION LOUVERS

(Each end of attic)

SIDE WALL

TERMINATED

EXHAUST PIPE

(ALTERNATE

LOCATION)

If air from outside is brought in for combustion and ventila­tion, the confined space must have two permanent open­ings. One opening shall be within 12 inches (305 mm) of
the top of the enclosure and one opening within 12 inches
(305 mm) of the bottom. These openings must communi­cate directly or by ducts with the outdoors or spaces (crawl
or attic) that freely communicate with the outdoors or indi­rectly through vertical ducts. Each opening shall have a
minimum free area of 1 square inch (645 mm

2

) per 4,000
Btu (1.17 kW) per hour of total input rating of all equipment
in the enclosure. See figures 4 and 5. When communicat­ing with the outdoors through horizontal ducts, each open­ing shall have a minimum free area of 1 square inch (645
mm

2

) per 2,000 Btu (.56 kW) per total input rating of all

equipment in the enclosure. See figure 6.

When ducts are used, they shall be of the same cross−sec­tional area as the free area of the openings to which they
connect. The minimum dimension of rectangular air ducts
shall be no less than 3 inches (75 mm). In calculating free
area, the blocking effect of louvers, grilles, or screens
must be considered. If the design and free area of protec­tive covering is not known for calculating the size opening
required, it may be assumed that wood louvers will have
20 to 25 percent free area and metal louvers and grilles
will have 60 to 75 percent free area. Louvers and grilles
must be fixed in the open position or interlocked with the
equipment so that they are opened automatically during
equipment operation.

FIGURE 5

EQUIPMENT IN CONFINED SPACE − ALL AIR FROM OUTSIDE

(All Air Through Ventilated Attic)

NOTE−The inlet and outlet air openings shall each have a free area of
at least one square inch per 4,000 Btu (645mm

2

per 1.17kW) per hour

of the total input rating of all equipment in the enclosure.

OUTLET

AIR

VENTILATION LOUVERS

(Each end of attic)

INLET AIR

(Ends 12" above

bottom)

G61MPV

ROOF TERMINATED

EXHAUST PIPE

SIDE WALL

TERMINATED

EXHAUST PIPE

(ALTERNATE

LOCATION)

FIGURE 6

G61MPV

EQUIPMENT IN CONFINED SPACE −

ALL AIR FROM OUTSIDE

OUTLET AIR

INLET AIR

NOTE−Each air duct opening shall have a free area of at least one
square inch per 2,000 Btu (645mm

2

per .59kW) per hour of the total

input rating of all equipment in the enclosure. If the equipment room
is located against an outside wall and the air openings communi­cate directly with the outdoors, each opening shall have a free area
of at least 1 square inch per 4,000 Btu (645mm

2

per 1.17kW) per

hour of the total input rating of all other equipment in the enclosure.

ROOF TERMINATED

EXHAUST PIPE

SIDE WALL

TERMINATED

EXHAUST PIPE

(ALTERNATE

LOCATION)

Page 9

Installation − Setting Equipment

WARNING

Do not install the furnace on its front or its back. Do
not connect the return air ducts to the back of the fur­nace. Doing so will adversely affect the operation of
the safety control devices, which could result in per­sonal injury or death.

Select a location that allows for the required clearances
that are listed on the unit nameplate. Also consider gas
supply connections, electrical supply, vent connection,
condensate trap and drain connections, and installation
and service clearances [24 inches (610 mm) at unit
front]. The unit must be level from front to back and side

to side.

The unit may be tilted slightly (maximum 1/2 in.) from
back to front to aid in the draining of the heat exchanger.
See figure 7.

NOTE − G61MPV−36B and −36C units with 1/2 hp blower
motors are equipped with three flexible legs and one rigid
leg. The rigid leg is equipped with a shipping bolt and a flat
white plastic washer (rather than the rubber mounting
grommet used with a flexible mounting leg). The bolt and

washer must be removed before the furnace is placed
into operation. After the bolt and washer have been re-

moved, the rigid leg will not touch the blower housing.

NOTE − G61MPV−60D−135 units are equipped with a ship­ping pad under the blower housing. Remove the shipping
pad prior to operation.

Allow for clearances to combustible materials as indicated
on the unit nameplate. Minimum clearances for closet or al­cove installations are shown in figures 8, 13 and 17.

WARNING

Blower access panel must be securely in place when
blower and burners are operating. Gas fumes, which
could contain carbon monoxide, can be drawn into
living space resulting in personal injury or death.

FIGURE 7

SETTING EQUIPMENT

UPFLOW APPLICATION DOWNFLOW APPLICATION

HORIZONTAL APPLICATION

FRONT VIEW

SIDE VIEW

FRONT VIEW

END VIEW

FRONT VIEW

SIDE VIEW

AIR FLOW

AIR FLOW

AIR FLOW

UNIT

FRONT

AIR FLOW

AIR FLOW

UNIT

FRONT

UNIT

FRONT

1/2"

max.

1/2"

max.

1/2"

max.

UNIT MUST BE LEVEL SIDE−TO−SIDE IN ALL APPLICATIONS.

UNIT SHOULD BE LEVEL FROM LEFT TO RIGHT BUT MAY BE

TILTED SLIGHTLY (MAX. 1/2") FROM BACK TO FRONT
TO AID IN THE DRAINING OF THE HEAT EXCHANGER.

Page 10

WARNING

Improper installation of the furnace can result in per­sonal injury or death. Combustion and flue products
must never be allowed to enter the return air system
or air in the living space. Use sheet metal screws and
joint tape to seal return air system to furnace.
In platform installations with furnace return, the fur­nace should be sealed airtight to the return air ple­num. A door must never be used as a portion of the
return air duct system. The base must provide a
stable support and an airtight seal to the furnace. Al­low absolutely no sagging, cracks, gaps, etc.
For no reason should return and supply air duct sys­tems ever be connected to or from other heating de­vices such as a fireplace or stove, etc. Fire, explo­sion, carbon monoxide poisoning, personal injury
and/or property damage could result.

Upflow Applications

The G61MPV gas furnace can be installed as shipped in
the upflow position. Refer to figure 8 for clearances.

Installation Clearances

Top

Bottom (Floor)

Left Side

Right Side

Top/Plenum 1 in. (25 mm)

*Front 0

Back 0

Sides 0†

Vent 0

Floor 0‡

*Front clearance in alcove installation must be 24 in. (610 mm).
Maintain a minimum of 24 in. (610 mm) for front service access.
†Allow proper clearances to accommodate condensate trap and
vent pipe installation.
‡For installations on a combustible floor, do not install the furnace
directly on carpeting, tile or other combustible materials other
than wood flooring.

FIGURE 8

Return Air −− Upflow Units

Return air can be brought in through the bottom or either
side of the furnace installed in an upflow application. If the
furnace is installed on a platform with bottom return, make

an airtight seal between the bottom of the furnace and the
platform to ensure that the furnace operates properly and
safely. The furnace is equipped with a removable bottom
panel to facilitate installation.

Markings are provided on both sides of the furnace cabinet
for installations that require side return air. Cut the furnace
cabinet at the maximum dimensions shown on page 2.

NOTE − When air volumes over 1800 cfm (850 L/s) are
required with 60C or 60D models in an upflow applica­tion, the following return air options are available:

1 − Return air from single side with transition which will

accommodate 20 x 25 x 1 in. (508 x 635 x 25 mm) air filter.
(Required to maintain proper air velocity.) See figure 9.

2 − Return air from single side with optional RAB Return

Air Base. See figure 11.

3 − Return air from bottom.

4 − Return air from both sides.

5 − Return air from bottom and

one side.

Refer to Engineering Handbook for additional information.

G61MPV applications which include side return air and
a condensate trap installed on the same side of the
cabinet require either a return air base or field−fabri­cated transition to accommodate an optional IAQ ac­cessory taller than 14.5".

Side Return Air

(with transition and filter)

FIGURE 9

Return Air

Plenum

Transition

20" X 25" X 1"

(508mm X635mm X 25mm)

Air Filter

Removing the Bottom Panel

Remove the two screws that secure the bottom cap to the
furnace. Pivot the bottom cap down to release the bottom
panel. Once the bottom panel has been removed, reinstall
the bottom cap. See figure 10.

Page 11

Removing the Bottom Panel

FIGURE 10

Screw

Bottom Panel

Bottom Cap

Optional Return Air Base

(Upflow Applications Only −− For use with B, C and D cabinets only)

FIGURE 11

NOTE− Optional Side Return Air Filter Kits are not for use with RAB Return Air Base.

1

Both the unit return air opening and the base return air opening must be covered by a single plenum or IAQ cabinet.
Minimum unit side return air opening dimensions for units requiring 1800 cfm or more of air (W x H): 23 x 11 in.
(584 x 279 mm).
The opening can be cut as needed to accommodate plenum or IAQ cabinet while maintaining dimensions shown.
Side return air openings must be cut in the field. There are cutting guides stenciled on the cabinet for the side return
air opening. The size of the opening must not extend beyond the markings on the furnace cabinet.

2

To minimize pressure drop, the largest opening height possible (up to 14 inches) is preferred.

NOTE− Optional Side Return Air Filter Kits are not for use with RAB Return Air Base.

1

Unit side return air

Opening

FRONT VIEW

SIDE VIEW

27−5/8 (702)

4

(102)

1

23 (584)

Overall

(Maximum)

OPTIONAL RAB

RETURN AIR BASE

23 (584)

7−1/4 (184)

7/8

(22)

3/4

(19)

1

22−7−16

(570)

Overall

(Maximum)

SIDE RETURN

AIR OPENINGS

(Either Side)

FURNACE

FRONT

14

(356)

AIR FLOW

5−5/8
(143)

1

Minimum
11 (279)

2

Maximum

14 (356)

21 (533) RAB−C (98M58)

24−1/2 (622) RAB−D (98M59)

17−1/2 (446) RAB−B (98M60)

Page 12

Setting an Upflow Unit

When the side return air inlets are used in an upflow ap­plication, it may be necessary to install leveling bolts on the
bottom of the furnace. Use field−supplied corrosion−resist­ant 5/16 inch machine bolts (4) and nuts (8). See figure 12.

NOTE − The maximum length of the bolt is 1−1/2 inches.

1 − Lie the furnace on its back and drill a 5/16 inch diame-

ter hole in each corner of the furnace’s bottom. See fig­ure 12 for the correct location of the holes. Drill through
the bottom panel and the bottom flange of the cabinet.

2 − Install one bolt and two nuts into each hole. Screw the

first nut onto a bolt and then insert the bolt into a hole. A
flat washer may be added between the nut and the bot­tom of the unit.

3 − Screw another nut onto the bolt on the inside of the fur-

nace base. A flat washer may be added between the
nut and the bottom of the unit.

4 − Adjust the outside nut to the appropriate height and

tighten the inside nut to secure the arrangement.

NOTE − The unit may be tilted back−to−front a maximum of
1". This will ensure proper draining of the heat exchanger.

FIGURE 12

1−3/4

(44)

1−3/4

(44)

3/8

(10)

1−3/4 (44)

3/8

(10)

3/8

(10)

3/8

(10)

1−3/4

(44)

Leveling Bolt Installation

Leveling Bolt

Locations

Leveling Bolt

Locations

Inches (mm)

Furnace Front

Furnace

Bottom

Downflow Applications

The unit may be installed three ways in downflow applica­tions: on non−combustible flooring, on combustible flooring
using an additive base, or on a reverse−flow cooling cabi­net. Do not drag the unit across the floor in the down-

flow position. Flange damage will result.

After unit has been properly set in place, position provided
logo over existing logo and affix sticker on front panel.

Refer to figure 13 for clearances in downflow applica­tions.

Downflow Application Installation Clearances

Top

Bottom

Left Side

Right Side

Top 0

*Front 0

Back 0

Sides 0†

Vent 0

Floor NC‡

*Front clearance in alcove installation must be 24 in. (610 mm).
Maintain a minimum of 24 in. (610 mm) for front service access.
†Allow proper clearances to accommodate condensate trap and
vent pipe installation.
‡The furnace may be installed on a combustible wood floor if an op­tional additive base is installed between the furnace and the com­bustible floor.

FIGURE 13

Installation on Non−Combustible Flooring

1 − Cut floor opening keeping in mind clearances listed on

unit rating plate. Also keep in mind gas supply connec­tions, electrical supply, flue and air intake connections
and sufficient installation and servicing clearances.
See table 1 for correct floor opening size.

2 − Flange warm air plenum and lower the plenum into the

opening.

3 − Set the unit over the plenum and seal the plenum to

the unit.

4 − Ensure that the seal is adequate.

TABLE 1

NON−COMBUSTIBLE FLOOR OPENING SIZE

Model No.

Front to Rear Side to Side

in. mm in. mm

B Cabinet (17.5") 19 − 3/4 502 16 − 5/8 422

C Cabinet (21") 19 − 3/4 502 20−1/8 511

D Cabinet (24.5") 19 − 3/4 502 23 − 5/8 600

NOTE − Floor opening dimensions listed are 1/4 inch (6 mm) larger than
the unit opening. See dimension drawing on page 2.

Page 13

Installation on Combustible Flooring

1 − When unit is installed on a combustible floor, an addi-

tive base must be installed between the furnace and
the floor. The base must be ordered separately. See
table 2 for opening size to cut in floor.

CAUTION

The furnace and additive base shall not be installed
directly on carpeting, tile, or other combustible ma­terial other than wood flooring.

TABLE 2

ADDITIVE BASE FLOOR OPENING SIZE

Cabinet

Width

Catalog
Number

Front to Rear Side to Side

in. mm in. mm

B Cabinet

(17.5")

11M60

22 559 18 − 3/4 476

C Cabinet

(21")

11M61

22 559 22 − 3/4 578

D Cabinet

(24.5")

11M62

22 559 25 − 3/4 654

2 − After opening is cut, set additive base into opening.

3 − Check fiberglass strips on additive base to make sure

they are properly glued and positioned.

4 − Lower supply air plenum into additive base until ple-

num flanges seal against fiberglass strips.

NOTE − Be careful not to damage fiberglass strips.
Check for a tight seal.

5 − Set the furnace over the plenum.

6 − Ensure that the seal between the furnace and plenum

is adequate.

G61MPV UNIT

SUPPLY AIR PLENUM

ADDITIVE BASE

PROPERLY

SIZED FLOOR

OPENING

FIGURE 14

Installation on Cooling Coil Cabinet

1 − Refer to reverse−flow coil installation instructions for

correctly sized opening in floor and installation of cabi­net.

2 − When cooling cabinet is in place, set and secure the

furnace according to the instructions that are provided
with the cooling coil. Secure the furnace to the cabinet.

3 − Seal the cabinet and check for air leaks.

Return Air Opening −− Downflow Units

Return air may be brought in only through the top opening
of a furnace installed in the downflow position.The follow­ing steps should be taken when installing plenum:

1 − Bottom edge of plenum should be flanged with a

hemmed edge (See figure 15 or 16).

2 − Sealing strips should be used to ensure an airtight seal

between the cabinet and the plenum.

3 − In all cases, plenum should be secured to top of fur-

nace using sheet metal screws.

4 − Make certain that an adequate seal is made.

FIGURE 15

SECURE FROM

OUTSIDE CABINET

PLENUM

(Field Provided)

SEALING STRIP
(Field Provided)

Side View

CABINET

SIDE PANEL

SECURE FROM

INSIDE CABINET

PLENUM

(Field Provided)

SEALING STRIP

(Field Provided)

Side View

CABINET

SIDE PANEL

FIGURE 16

Horizontal Applications

The G61MPV furnace can be installed in horizontal ap­plications with either right− or left−hand air discharge.

The G61MPV may also be installed as a unit heater. Either
suspend the furnace as shown in figure 18, or install the
furnace on a field−fabricated raised platform. The unit
must be supported at both ends and beneath the blower
deck to prevent sagging.

Refer to figure 17 for clearances in horizontal applications.

Page 14

Horizontal Application

Installation Clearances

Top

Left End Right End

Right−Hand Discharge

Left−Hand Discharge

Top

Bottom (Floor)**

Bottom (Floor)**

Left End Right End

Top 0

Front* 0

Back 0

Ends 0

Vent 0

Floor 0‡

*Front clearance in alcove installation must be 24 in. (610 mm).
Maintain a minimum of 24 in. (610 mm) for front service access.
**A 5−1/2 service clearance must be maintained below the unit to
provide for servicing of the condensate trap.
‡For installations on a combustible floor, do not install the furnace
directly on carpeting, tile or other combustible materials other
than wood flooring.

FIGURE 17

Suspended Installation of Horizontal Unit

NOTE − If unit is suspended in attic or crawl space, horizon­tal support kit (Cat No. 56J18 ordered separately) must be
used to ensure proper unit support and coil drainage.

1 − Select location for unit keeping in mind service and

other necessary clearances. See figure 17.

2 − Provide service platform in front of unit.

3 − If unit is installed above finished space, fabricate a

drain pan fitted with a 1/2 inch or 3/4 inch N.P.T. fitting.

4 − Using 3/8 inch rods and support frame kit or field−fabri-

cated supports, fabricate suspension hangers, keep­ing in mind front service access clearances.

5 − Mount unit on support frame as shown in figure 18.

6 − Continue with exhaust, condensate and intake line

piping instructions.

7 − If unit is suspended above finished space, hang the

field−provided drain pan below the support frame as
shown in figure 18. Leave 5−1/2 inches for service
clearance below unit for condensate trap.

8 − Route auxiliary drain line so that water draining from

this outlet will be easily noticed by the homeowner. If
necessary, run the condensate line into a condensate
pump to meet drain line slope requirements. The
pump must be rated for use with condensing furnaces.
Protect the condensate discharge line from the pump
to the outside to avoid freezing.

FIGURE 18

BLOWER ACCESS PANEL

3/8 in. RODS

SUPPORT FRAME

INTAKE/EXHAUST

CONNECTION

TYPICAL HORIZONTAL CEILING APPLICATION

DRAIN PAN

(to protect finished space)

Platform Installation of Horizontal Unit

1 − Select location for unit keeping in mind service and

other necessary clearances. See figure 17.

2 − Construct a raised wooden frame and cover frame

with a plywood sheet. Provide a service platform in
front of unit. If unit is installed above finished space,
fabricate a drain pan to be installed under unit.
When installing the unit in a crawl space, a proper sup­port platform may be created using cement blocks and
the horizontal support frame kit (ordered separately,
Lennox part number 56J18). Position the support
frame on top of the blocks and install the unit on the
frame. Leave 5−1/2 inches for service clearance for
condensate trap.

3 − Route auxiliary drain line so that water draining from

this outlet will be easily noticed by the homeowner. If
necessary, run the condensate line into a condensate
pump to meet drain line slope requirements. The
pump must be rated for use with condensing furnaces.
Protect the condensate discharge line from the pump
to the outside to avoid freezing.

Page 15

4 − Set unit in drain pan as shown in figure 19. Leave 5−1/2

inches for service clearance below unit for condensate
trap.

5 − Continue with exhaust, condensate and intake piping

installation according to instructions.

INTAKE PIPE

*GAS

CONNECTOR

SERVICE PLATFORM

RAISED

PLATFORM

CONDENSATE LINE

*Gas connector may be
used for Canadian
installation if accept­able by local authority
having jurisdiction.

EXHAUST PIPE

FIGURE 19

G61MPV Installed in Unit Heater Applications

The G61MPV may also be installed as a unit heater. Either
suspend the furnace from roof rafters or floor joists, as
shown in figure 18, or install the furnace on a field−fabri­cated raised platform, as shown in figure 19. The unit must
be supported at both ends and beneath the blower deck to
prevent sagging. The condensate trap must be installed
where it can be serviced at a later date.

Unit Heater Discharge Duct Guidelines

A field−fabricated and installed discharge air duct and grille
cabinet is suitable for use with the G61MPV heater. Keep
the following items in mind when constructing the cabinet.

1 − Outer dimensions of cabinet should match those of the

unit heater, so the duct/grille cabinet installs flush with
the unit heater cabinet. See figure 20.

2 − Flange both ends of duct/grille cabinet so that screws

can be used to secure cabinet to discharge end of unit
heater.

3 − To ensure proper operation, the duct/grille cabinet

must be at least 18 inches long.

4 − Use #10−16 x 1/2 inch sheet metal screws to secure

duct/grille cabinet to unit, taking care not to damage in­ternal components of unit heater when drilling holes or
installing screws. See figure 20.

5 − Use adjustable, double−deflection grille(s) to distribute

discharge air. Adjust static pressure to be in the 0.06
inch to 0.10 inch w.c. range.

FIGURE 20

18 in.

MIN.

NOTE − When installing duct/grille cabinet, take care not to damage internal unit

heater components when drilling holes or installing screws.

DRAIN PAN

(to protect

finished

space)

Return Air −− Horizontal Applications

Return air may be brought in only through the end of a fur­nace installed in the horizontal position. The furnace is
equipped with a removable bottom panel to facilitate
installation. See figure 10.

Filters

This unit is not equipped with a filter or rack. A field−pro­vided filter is required for the unit to operate properly. Table
3 lists recommended filter sizes.

A filter must be in place whenever the unit is operating.

NOTE − In upflow applications where side return air fil­ter is installed on same side as the condensate trap, fil­ter rack must be installed beyond condensate trap to
avoid interference.

TABLE 3

Furnace

Cabinet Width

Filter Size

Side Return Bottom Return

17−1/2" 16 X 25 X 1 (1) 16 X 25 X 1 (1)

21" 16 X 25 X 1 (1) 20 X 25 X 1 (1)

24−1/2" 16 X 25 X 1 (2) 24 X 25 X 1 (1)

Page 16

Duct System

Use industry-approved standards to size and install the
supply and return air duct system. This will result in a quiet
and low-static system that has uniform air distribution.

NOTE − Operation of this furnace in heating mode (indoor
blower operating at selected heating speed) with an exter­nal static pressure which exceeds 0.8 inches w.c. may re­sult in erratic limit operation.

Supply Air Plenum

If the furnace is installed without a cooling coil, a removable
access panel should be installed in the supply air duct. The
access panel should be large enough to permit inspection
(by reflected light) of the heat exchanger for leaks after the
furnace is installed. If present, this access panel must al­ways be in place when the furnace is operating and it must
not allow leaks into the supply air duct system.

Return Air Plenum

NOTE − Return air must not be drawn from a room
where this furnace, or any other gas−fueled ap­pliance (i.e., water heater), or carbon monoxide−
producing device (i.e., wood fireplace) is installed.

When return air is drawn from a room, a negative pres­sure is created in the room. If a gas appliance is operating
in a room with negative pressure, the flue products can
be pulled back down the vent pipe and into the room. This
reverse flow of the flue gas may result in incomplete com­bustion and the formation of carbon monoxide gas. This
toxic gas might then be distributed throughout the house
by the furnace duct system.

Return air can be brought in through the bottom or either
side of the furnace. If a furnace with bottom return air is
installed on a platform, make an airtight seal between the
bottom of the furnace and the platform to ensure that the
unit operates properly and safely. Use fiberglass sealing
strips, caulking, or equivalent sealing method between the
plenum and the furnace cabinet to ensure a tight seal. If a
filter is installed, size the return air duct to fit the filter frame.

Pipe & Fittings Specifications

All pipe, fittings, primer and solvent cement must conform
with American National Standard Institute and the Ameri­can Society for Testing and Materials (ANSI/ASTM) stan­dards. The solvent shall be free flowing and contain no
lumps, undissolved particles or any foreign matter that ad-

versely affects the joint strength or chemical resistance of
the cement. The cement shall show no gelation, stratifica­tion, or separation that cannot be removed by stirring. Re­fer to the table 4 below for approved piping and fitting
materials.

CAUTION

Solvent cements for plastic pipe are flammable liq­uids and should be kept away from all sources of
ignition. Do not use excessive amounts of solvent
cement when making joints. Good ventilation should
be maintained to reduce fire hazard and to minimize
breathing of solvent vapors. Avoid contact of cement
with skin and eyes.

TABLE 4

PIPING AND FITTINGS SPECIFICATIONS

PIPE & FITTING MATERIAL

ASTM

SPECIFICATION

Schedule 40 PVC (Pipe) D1785
Schedule 40 PVC (Cellular Core Pipe) F891

Schedule 40 PVC (Fittings) D2466

Schedule 40 CPVC (Pipe) F441

Schedule 40 CPVC (Fittings) F438

SDR−21 PVC or SDR−26 PVC (Pipe) D2241

SDR−21 CPVC or SDR−26 CPVC (Pipe) F442

Schedule 40 ABS Cellular Core DWV (Pipe) F628

Schedule 40 ABS (Pipe) D1527

Schedule 40 ABS (Fittings) D2468

ABS−DWV (Drain Waste & Vent)
(Pipe & Fittings)

D2661

PVC−DWV (Drain Waste & Vent)
Pipe & Fittings)

D2665

PRIMER & SOLVENT CEMENT

ASTM

SPECIFICATION

PVC & CPVC Primer F656
PVC Solvent Cement D2564

CPVC Solvent Cement F493

ABS Solvent Cement D2235

PVC/CPVC/ABS All Purpose Cement For
Fittings & Pipe of the same material

D2564, D2235, F493

ABS to PVC or CPVC Transition Solvent
Cement

D3138

CANADA PIPE & FITTING & SOLVENT

CEMENT

MARKING

PVC & CPVC Pipe and Fittings

ULCS636

PVC & CPVC Solvent Cement

ABS to PVC or CPVC Transition Cement

Page 17

Use PVC primer and solvent cement or ABS solvent cement
meeting ASTM specifications, refer to Table 4. As an alter­nate, use all purpose cement, to bond ABS, PVC, or CPVC
pipe when using fittings and pipe made of the same materi­als. Use transition solvent cement when bonding ABS to ei­ther PVC or CPVC.

Low temperature solvent cement is recommended. Metal or
plastic strapping may be used for vent pipe hangers. Uni­formly apply a liberal coat of PVC primer for PVC or use a
clean dry cloth for ABS to clean inside socket surface of fit­ting and male end of pipe to depth of fitting socket.

Canadian Applications Only − Pipe, fittings, primer
and solvent cement used to vent (exhaust) this ap­pliance must be certified to ULC S636 and supplied by a
single manufacturer as part of an approved vent (ex­haust) system. When bonding the vent system to the fur­nace, use ULC S636 approved One−Step Transition Ce­ment to bond the pipe to the flue collar, or to bond the 90°
elbow or reducing 90° elbow to the flue collar. In addi­tion, the first three feet of vent pipe from the furnace flue
collar must be accessible for inspection.

Table 5 lists the available exhaust termination kits, as well
as vent pipe equivalencies which must be used when siz­ing vent pipe. All Lennox vent terminations are PVC.

Page 18

TABLE 5

OUTDOOR TERMINATION KITS AND CORRESPONDING EQUIVALENCIES

UNIT

MODEL

VENT

PIPE
DIA.

(in.)

Vent Pipe Length Equivalency (feet)

Outdoor
Exhaust

Accelera-

tor

(Dia. X

Length)

Outdoor
Exhaust
Acceler-

ator

(Dia. X

Length)

1−1/2"

Concentric

Kit

2"

Concentric

Kit

3"

Concen-

tric Kit

2" Wall

Plate Kit

3" Wall

Plate Kit

2" Wall

Ring

Kit

Flush Mount

Termination

1−1/2" X

12"

2" X 12"

71M80

or

44W92

69M29

or

44W92

60L46

or

44W93

22G44

or

30G28

44J40

or

81J20

15F74

51W11

with

1−1/2

accelera-

tor

51W11
without

1−1/2" ac-

celerator

36B−045

2 4

Not

Allowed

12

Not

Allowed

Not

Allowed

4 4* 4 4

Not

Allowed

2−1/2 5

Not

Allowed

15

Not

Allowed

Not

Allowed

5 5* 5 7****

Not

Allowed

3 7

Not

Allowed

21

Not

Allowed

Not

Allowed

7 7* 7 7

Not

Allowed

4 14

Not

Allowed

42

Not

Allowed

Not

Allowed

14 14* 14

Not

Allowed

Not

Allowed

36B−070
36B−071

2 4

Not

Allowed

12

Not

Allowed

Not

Allowed

4 4* 4 4

Not

Allowed

2−1/2 5

Not

Allowed

15

Not

Allowed

Not

Allowed

5 5* 5 7****

Not

Allowed

3 8

Not

Allowed

24

Not

Allowed

Not

Allowed

8 8* 8 8

Not

Allowed

4 14

Not

Allowed

42

Not

Allowed

Not

Allowed

14 14* 14

Not

Allowed

Not

Allowed

36B−091

60C−090

2

Not

Allowed

1

Not

Allowed

3 3

Not

Allowed

1 1** 4

Not

Allowed

2−1/2

Not

Allowed

2

Not

Allowed

6 6

Not

Allowed

2 2** 7****

Not

Allowed

3

Not

Allowed

2

Not

Allowed

6 6

Not

Allowed

2 2** 8

Not

Allowed

4

Not

Allowed

4

Not

Allowed

12 12

Not

Allowed

4 4**

Not

Allowed

Not

Allowed

60C−110
60C−111

2

Not

Allowed

1

Not

Allowed

3 3

Not

Allowed

1 1**

Not

Allowed

1

2−1/2

Not

Allowed

2

Not

Allowed

6 6

Not

Allowed

2 2***

Not

Allowed

4****

3

Not

Allowed

2

Not

Allowed

6 6

Not

Allowed

2 2***

Not

Allowed

7

4

Not

Allowed

4

Not

Allowed

12 12

Not

Allowed

4 4***

Not

Allowed

Not

Allowed

60D−135

3

Not

Allowed

6

Not

Allowed

Not

Allowed

15

Not

Allowed

6 6***

Not

Allowed

7

4

Not

Allowed

10

Not

Allowed

Not

Allowed

25

Not

Allowed

10 10***

Not

Allowed

Not

Allowed

*Requires field−provided and installed 1−1/2" exhaust accelerator.
**Requires field−provided and installed 2" exhaust accelerator.
***For use only in non−direct vent applications, when snow riser is not required. Re­quires field−provided and installed 2" exhaust accelerator.
**** Requires field−provided and installed 2"−2−1/2" coupling on G61MPV−36B−045,
G61MPV−36B−070, 071, G61MPV−36B−090,091 and G61MPV−60C−110 furnaces

 Termination kits 44W92, 44W93, 30G28 & 81J20 are ULC−636 approved for Cana­dian Installation.

 The 44W92 Concentric kit is provided with a 1−1/2" accelerator which must be
installed on the exhaust outlet when this kit is used with the G61MPV−36B−045,
G61MPV−36B−070 & 071 furnaces.

Page 19

Vent Piping Guidelines

The G61MPV can be installed as either a Non−Direct
Vent or a Direct Vent gas central furnace.

NOTE − In Non-Direct Vent installations, combustion air is
taken from indoors and flue gases are discharged outdoors.
In Direct Vent installations, combustion air is taken from out­doors and flue gases are discharged outdoors.

Intake and exhaust pipe sizing in Direct Vent applications
and exhaust pipe sizing in Non-Direct Vent applications −−
Size pipe according to tables 6 and 7. Table 6 lists the mini­mum equivalent vent pipe lengths permitted. Table 7 lists
the maximum equivalent pipe lengths permitted.

Maximum vent length is defined as:

Total length (linear feet) of pipe,

Plus Equivalent length (feet) of fittings,
Plus Equivalent length (feet) of termination.
NOTE − Include ALL pipe and ALL fittings, both in
doors and outdoors.

Regardless of the diameter of pipe used, the standard roof
and wall terminations described in section Exhaust Piping
Terminations should be used. Exhaust vent termination
pipe is sized to optimize the velocity of the exhaust gas as
it exits the termination. Refer to table 8.

NOTE − The exhaust pipe should be offset a minimum of 12
inches to avoid the possibility of water droplets being re­leased from the exhaust termination. The minimum ex­haust vent length is 15 ft. Shorter exhaust vent lengths may
result in the discharge of water droplets from the exhaust
termination, in spite of the 12−inch vertical offset. See fig­ure 21.

Each 90° elbow (including those provided with the furnace)
of any diameter is equivalent to 5 feet (1.52m) of vent pipe
of the same diameter. Two 45° elbows are equivalent to
one 90° elbow of the same diameter. One 45° elbow is
equal to 2.5 feet (.76m) of vent pipe of the same diameter.

NOTE − On G61MPV−071, −091 and −111 units, sweep el­bows must be used for all 90° elbows in the venting
system when 2", 2−1/2" or 3" vent pipe is used. On
G61MPV−135, sweep elbows must be used for all 90° el­bows in the venting system when 3" vent pipe is used.
Sweep elbows are recommended for use in vent sys­tems of other G61MPV units.

In some applications which permit the use of several differ­ent sizes of vent pipe, a combination vent pipe may be
used. Contact Lennox’ Application Department for assis­tance in sizing vent pipe in these applications.

FIGURE 21

Exhaust Pipe Offset

*12" Min.

*12" Min.

*12" Min.

12" Min.

Upflow and Downflow Application

Rooftop Termination

Upflow and Downflow Application

Side Wall Termination

Horizontal Application

Rooftop Termination

Horizontal Application

Side Wall Termination

*A minimum of 1/4" (6mm) drop for each 12" (305mm) of horizontal run is mandatory for drainage

Page 20

NOTE − The flue collar on all models is sized to accommo­date 2" Schedule 40 flue pipe. When vent pipe which is
larger than 2" must be used in an upflow application, a 2"
elbow must be applied at the flue collar in order to proper­ly transition to the larger diameter flue pipe. This elbow
must be added to the elbow count used to determine ac­ceptable vent lengths. Assign an equivalent feet value to
this elbow according to the larger size pipe being used.
Contact the Application Department for more information
concerning sizing of vent systems which include multiple
pipe sizes.

Use the following steps to correctly size vent pipe diameter.

Refer to Vent Pipe Size Determination Worksheet on
page 65.

1 − Determine the vent termination and its corresponding

equivalent feet value according to table 5.

2 − Determine the number of 90° elbows required for both

indoor and outdoor (e.g. snow riser) use. Calculate the
corresponding equivalent feet of vent pipe.

3 − Determine the number of 45° elbows required for both

indoor and outdoor use. Calculate the corresponding
equivalent feet of vent pipe.

4 − Determine the length of straight pipe required.

5 − Add the total equivalent feet calculated in steps 1

through 4 and compare that length to the maximum
values given in table 7 for the proposed vent pipe di­ameter. If the total equivalent length required exceeds
the maximum equivalent length listed in the appropri­ate table, evaluate the next larger size pipe.

IMPORTANT

Do not use screens or perforated metal in exhaust
terminations. Doing so will cause freeze−ups and
may block the terminations.

TABLE 6

MINIMUM VENT PIPE LENGTHS

G61MPV

MODEL

MIN. EQUIV.

VENT LENGTH

EXAMPLE

045, 070,
071, 090,

091

15 ft.*

5 ft. plus 2 elbows of 2", 2−1/2", 3"

or 4" diameter pipe

110

5 ft. plus 2 elbows of 2−1/2" 3" or 4"

diameter pipe

135***

5 ft. plus 2 elbows of 3" or 4"

diameter pipe

*Any approved termination may be added to the minimum equivalent length
listed.

**G61MPV−60C−110 and −111 must have 90° street ell (supplied or field re­placement Canadian kit) installed directly into unit flue collar.

***G61MPV−60D−135 must have 3" to 2" reducing ell (supplied or field replace­ment Canadian kit) installed directly into unit flue collar.

TABLE 7

MAXIMUM VENT PIPE LENGTHS

ALTITUDE

G61MPV

MODEL

MAXIMUM EQUIVALENT VENT

LENGTH FEET

2"

PIPE

2−1/2"

PIPE

3"

PIPE4"PIPE

0 − 4500

(0 − 1371 m)

045 59 65 77 234
070 59 65 78 214

071† 59 65 78 214

090 26 42 72 204

091† 26 42 72 204

110* n/a 32 72 179

111*† n/a 32 72 179

135**‡ n/a n/a 61 160

4501−7500

(1372−2286 m)

045 59 65 77 234
070 59 65 78 214

071† 59 65 78 214

090 26 42 72 204

091† 26 42 72 204

110* n/a 32 72 179

111*† n/a 32 72 179

135**‡ n/a n/a 46 160

7501 − 10000

(2287 − 3048 m)

045 59 65 77 234
070 59 65 78 214

071† 59 65 78 214

090 26 42 72 204

091† 26 42 72 204

110* n/a 32 72 179

111*† n/a 32 72 179

135**‡ n/a n/a 46 160

n/a −− Not allowed.
*G61MPV−60C−110 and −111 must have 90° street ell (supplied or field replace-

ment Canadian kit) installed directly into unit flue collar.
**G61MPV−60D−135 must have 3" to 2" reducing ell (supplied or field replace-

ment Canadian kit) installed directly into unit flue collar.

†On G61MPV−071, −091 and −111 units, sweep elbows must be used
for all 90° elbows in the venting system when 2", 2−1/2" or 3" vent
pipe is used. Sweep elbows are recommended for use in vent sys­tems of other G61MPV units.

‡On G61MPV−60D−135 units, sweep elbows must be used for all 90° el­bows in the vent system when 3" vent pipe is used.

Joint Cementing Procedure

All cementing of joints should be done according to the
specifications outlined in ASTM D 2855.

WARNING

DANGER OF EXPLOSION!

Fumes from PVC glue may ignite during system
check. Allow fumes to dissipate for at least 5 minutes
before placing unit into operation.

1 − Measure and cut vent pipe to desired length.

2 − Debur and chamfer end of pipe, removing any ridges

or rough edges. If end is not chamfered, edge of pipe
may remove cement from fitting socket and result in a
leaking joint.

3 − Clean and dry surfaces to be joined.

4 − Test fit joint and mark depth of fitting on outside of pipe.

Page 21

5 − Uniformly apply a liberal coat of PVC primer for PVC or

use a clean dry cloth for ABS to clean inside socket
surface of fitting and male end of pipe to depth of fitting
socket.

NOTE − Furnace flue collar and air inlet fitting are both
made of ABS material. Usetransition solvent cement
when bonding ABS to either PVC or CPVC, refer to the
procedure specified in ASTM D3138..

6 − Promptly apply solvent cement to end of pipe and in-

side socket surface of fitting. Cement should be ap­plied lightly but uniformly to inside of socket. Take
care to keep excess cement out of socket. Apply sec­ond coat to end of pipe.

NOTE − Time is critical at this stage. Do not allow prim­er to dry before applying cement.

7 − Immediately after applying last coat of cement to pipe,

and while both inside socket surface and end of pipe
are wet with cement, forcefully insert end of pipe into
socket until it bottoms out. Turn PVC pipe 1/4 turn dur­ing assembly (but not after pipe is fully inserted) to dis­tribute cement evenly. DO NOT turn ABS or cellular
core pipe.

NOTE − Assembly should be completed within 20 sec­onds after last application of cement. Hammer blows
should not be used when inserting pipe.

8 − After assembly, wipe excess cement from pipe at end

of fitting socket. A properly made joint will show a
bead around its entire perimeter. Any gaps may indi­cate a defective assembly due to insufficient solvent.

9 − Handle joints carefully until completely set.

Venting Practices

The thickness of construction through which vent pipes
may be installed is 24" (610mm) maximum and 3/4"
(19mm) minimum. If a G61MPV furnace replaces a furnace
which was commonly vented with another gas appliance,
the size of the existing vent pipe for that gas appliance must
be checked. Without the heat of the original furnace flue
products, the existing vent pipe is probably oversized for
the single water heater or other appliance. The vent should
be checked for proper draw with the remaining appliance.

1 − Use recommended piping materials for exhaust pip-

ing.

2 − Secure all joints so that they are gas-tight using ap-

proved cement.
Suspend piping using hangers at a minimum of every 5

feet (1.52m) for schedule
40 PVC and every 3 feet
(.91m) for ABS−DWV, PVC−
DWV, SPR−21 PVC, and
SDR−26 PVC piping. A suit­able hanger can be fabri­cated by using metal or
plastic strapping or a large
wire tie.

3 − In areas where piping penetrates joists or interior

walls, hole must be large enough to allow clearance on
all sides of pipe through center of hole using a hanger.

4 − Isolate piping at the point where it exits the outside wall

or roof in order to prevent transmission of vibration to
the structure.

5 − When furnace is installed in a residence where unit is

shut down for an extended period of time, such as a
vacation home, make provisions for draining conden­sate collection trap and lines.

Exhaust Piping (Figures 23 and 24)

NOTE − A 2" diameter PVC street ell is located on the
blower deck of 60C−110 and 60C−111 units. In upflow or
downflow applications the street ell must be

glued us­ing transition solvent cement directly into the unit flue col­lar. See figure 23. A 3" to 2" PVC reducing ell is located on
the blower deck of the 60D−135 units. In upflow or
downflow applications, the reducing ell must be

glued
using transition solvent cement directly into the unit flue
collar.

1 − Choose the appropriate side for venting in upflow or

downflow positions. Exhaust piping exits from the top
of the unit in horizontal air discharge applications.
Glue the field−provided exhaust vent pipe (or provided
street ell or reducing ell in upflow or downflow applica­tions) to the flue collar. All PVC cement joints should
be made according to the specifications outlined in
ASTM D 2855. Refer to pipe and fittings specifications
and gluing procedures.

IMPORTANT

Exhaust piping and condensate trap must be
installed on the same side of the unit in upflow and
dowflow applications or use alternate drain kit
76M20.

2 − All horizontal runs of exhaust pipe must slope back to-

ward unit. A minimum of 1/4" (6mm) drop for each 12"
(305mm) of horizontal run is mandatory for drainage.
Horizontal runs of exhaust piping must be supported ev­ery 5 feet (1.52m) using hangers.

NOTE − Exhaust piping should be checked carefully to
make sure there are no sags or low spots.

3 − On the opposite side of the cabinet, glue the provided

2" ABS vent plug into the unused ABS flue collar with
ABS or all purpose solvent cement.

4 − Route piping to outside of structure. Continue with

installation following instructions given in piping ter­mination section.

CAUTION

Do not discharge exhaust into an existing stack or
stack that also serves another gas appliance. If verti­cal discharge through an existing unused stack is re­quired, insert PVC pipe inside the stack until the end
is even with the top or outlet end of the metal stack.

CAUTION

The exhaust vent pipe operates under positive pres­sure and must be completely sealed to prevent leak­age of combustion products into the living space.

FIGURE 22

STRAPPING

(metal, plastic

or large wire

ties)

Page 22

TYPICAL EXHAUST PIPE CONNECTIONS AND CONDENSATE TRAP INSTALLATION

IN UPFLOW OR DOWNFLOW DIRECT OR NON−DIRECT VENT APPLICATIONS

(Right−Hand Exit in Upflow Application Shown)

FIGURE 23

VENT PLUG

(Must be

glued in

place)

PLUG

PLUG

CONDENSATE

TRAP

(Must be installed

on same side as

exhaust piping)

PLUG

G61MPV−110, −111,

−135 with

3" OR 4" vent pipe

2"

G61MPV−070,

−071, −090, −091

with 2−1/2", 3", or

4" vent pipe

TRANSITION

(use only if 4"

pipe is

required)

4"

2"

2" max

length

2−1/2",
3", OR

4"

TRANSITION

2"

2"

G61MPV−110,

−111 with

2−1/2", 3", OR 4"

vent pipe

*2"

TRANSITION

2−1/2",

3", OR

4"

2"

2"

or

45°

MAX

45°

MAX

SIDE VIEW

*2" diameter street elbow provided.

** Street elbow may be used on −045, −070, 071, −090, −091.

3" to 2" REDUCING ELBOW

(provided)

**

2" max

length

FIGURE 24

TYPICAL EXHAUST PIPE CONNECTIONS

HORIZONTAL DIRECT OR

NON−DIRECT VENT APPLICATIONS

(Horizontal Right−Hand Air Discharge Application Shown)

2"

2"

2"

*2"

2−1/2",
3", OR

4"

DO NOT transition
from smaller to larger
pipe size in horizontal
runs of exhaust pipe.

TRANSITION

−36B−045

−36B−070

−36B−071

−36C−090

−60C−090

−60C−091

−60C−110*

−60C−111*

−60D−135*

−36B−045

−36B−070

−36B−071

−36C−090

−60C−090

−60C−091

*Limit pipe
length to 2" in −110, −111,

−135 applications.

Intake Piping

The G61MPV furnace may be installed in either direct vent
or non−direct vent applications. In non−direct vent applica-
tions, when intake air will be drawn into the furnace from the
surrounding space, the indoor air quality must be consid­ered and guidelines listed in Combustion, Dilution and Ven­tilation Air section must be followed.

The G61MPV unit is designed for either left−side or right−
side air intake connections in either upflow or downflow ap­plications. In horizontal applications, air intake must be
brought in through the top. Intake air piping is independent
of exhaust piping.

Follow the next four steps when installing the unit in direct
vent applications, where combustion air is taken from
outdoors and flue gases are discharged outdoors. The

provided air intake screen must not be used in direct
vent applications.

1 − Use transition solvent cement to connect PVC pipe to

the ABS slip connector located on the side of the burn­er box.

2 − Use a sheet metal screw to secure the intake pipe to

the connector, if desired. A pilot indentation is pro­vided in the slip connector to assist in locating and
starting the fastener.

3 − Glue the provided 2" ABS plug into the unused ABS air

intake connector on the opposite side of the cabinet with
ABS all pupose cement.

4 − Route piping to outside of structure. Continue with

installation following instructions given in general
guide lines for piping terminations and in intake and
exhaust piping terminations for direct vent sections.
Refer to figure 25 for pipe sizes.

Page 23

TYPICAL AIR INTAKE PIPE CONNECTIONS

UPFLOW OR DOWNFLOW DIRECT VENT APPLICATIONS

(Right−Hand Exit in Upflow Application Shown)

FIGURE 25

PLUG

(Must be

glued in

place)

*Limit pipe length to 4" in

−110, −111, −135 applications.

−36B−045

−36B−070

−36B−071

−36C−090

−60C−090

−60C−091

−36B−045

−36B−070

−36B−071

−36C−090

−60C−090

−60C−091

−60C−110*

−60C−111*

−36B−045

−36B−070

−36C−071

−36C−090

−60C−090

−60C−091

−60C−110*

−60C−111*

−60D−135*

*2"

TRANSITION

2−1/2",

3" OR

4

2

2

2

2−1/2",

3" OR

4

TRANSITION

2

2

2

FIGURE 26

TYPICAL AIR INTAKE PIPE CONNECTIONS

HORIZONTAL DIRECT VENT APPLICATIONS

(Horizontal Right−Hand Air Discharge Application Shown)

*Limit pipe
length to 4" in

−110, −111, −135
applications.

−36B−045

−36B−070

−36B−071

−36C−090

−60C−090

−60C−091

−60C−110

−60C−111

−60D−135*

−36B−045

−36B−070

−36B−071

−36C−090

−60C−090

−60C−091

−60C−110

−60C−111

−36B−045

−36B−070

−36B−071

−36C−090

−60C−090

−60C−091

2”

2”

2”

TRANSITION

2”

2−1/2”,

3” OR 4”

2”

*2”

TRANSITION

2−1/2”,

3” OR 4”

Follow the next three steps when installing the unit in Non­Direct Vent applications where combustion air is taken
from indoors and flue gases are discharged outdoors.

FIGURE 27

PLUG

(Must be

glued in

place)

TYPICAL AIR INTAKE PIPE CONNECTIONS

UPFLOW OR HORIZONTAL NON−DIRECT

VENT APPLICATIONS

(Right−Hand Exit in Upflow Application Shown)

6 in. Max.

INTAKE

DEBRIS

SCREEN

(Provided)

NOTE − Debris screen and elbow may be rotated, so that
screen may be positioned to face forward, backward or
downward.

Page 24

TYPICAL AIR INTAKE PIPE CONNECTIONS

DOWNFLOW NON−DIRECT VENT APPLICATIONS

(Right−Hand Exit in Downflow Applications Shown)

FIGURE 28

PLUG

(Must be

glued in

place)

6 in. Max.

PLUG

(Must be

glued in

place)

Downflow Additive Flloor Base

18 in.

Downflow

Evaporator

Coil

2"

2" SWEEP

ELL

2" SWEEP ELL

INTAKE DEBRIS

SCREEN

(Provided)

INTAKE
DEBRIS

SCREEN

(Provided)

NOTE − Debris screen and sweep ell may be rotated, so that
screen may be positioned to face forward, backward or to the side.

1 − Use field−provided materials and the factory−provided

air intake screen to route the intake piping as shown in
figures 27 and 28. Maintain a minimum clearance of 3"
(76mm) around the air intake opening. The air intake
opening (with the protective screen) should always be
directed either downward or straight out. Use 2" pipe
and fittings only and make sure that the air intake does
not extend more than 6" beyond the G61MPV cabinet.

The air intake connector must not be located near
the floor. To avoid this complication in downflow
applications which do not include a downflow

evaporator coil, the intake air routing should be modi-

fied as shown in figure 28.

2 − Use a sheet metal screw to secure the intake pipe to

the connector, if desired. A pilot indentation is pro­vided in the slip connector to assist in locating and
starting the fastener.

3 − Glue the provided 2" ABS plug into the unused ABS air

intake connector on the opposite side of the cabinet
with ABS or all purpose solvent cement.

Page 25

General Guidelines for Vent Terminations

In Non-Direct Vent applications, combustion air is taken
from indoors and the flue gases are discharged to the out­doors. The G61MPV is then classified as a non-direct
vent, Category IV gas furnace.

In Direct Vent applications, combustion air is taken from
outdoors and the flue gases are discharged to the out­doors. The G61MPV is then classified as a direct vent,
Category IV gas furnace.

In both Non-Direct Vent and Direct Vent applications, the
vent termination is limited by local building codes. In the
absence of local codes, refer to the current National Fuel
Gas Code ANSI Z223−1/NFPA 54 in U.S.A., and current
CSA−B149 Natural Gas and Propane Installation Codes in
Canada for details.

Position termination according to location given in figure 29
or 30. In addition, position termination so it is free from any
obstructions and 12" above the average snow accumula­tion.

At vent termination, care must be taken to maintain
protective coatings over building materials (prolonged
exposure to exhaust condensate can destroy protective
coatings). It is recommended that the exhaust outlet not be
located within 6 feet (1.8m) of a condensing unit because
the condensate can damage the painted coating.

NOTE − If winter design temperature is below 32°F (0°C),
exhaust piping should be insulated with 1/2" (13mm), Ar­maflex or equivalent when run through unheated space.
Do not leave any surface area of exhaust pipe open to out­side air; exterior exhaust pipe should be insulated with 1/2"
(13mm) Armaflex or equivalent. In extreme cold climate
areas, 3/4" (19mm) Armaflex or equivalent may be neces­sary. Insulation on outside runs of exhaust pipe must be
painted or wrapped to protect insulation from deterioration.
Exhaust pipe insulation may not be necessary in some
specific applications.
NOTE − During extremely cold temperatures, below
approximately 20°F (6.7°C), units with long runs of vent
pipe through unconditioned space, even when insulated,
may form ice in the exhaust termination that prevents the
unit from operating properly. Longer run times of at least 5
minutes will alleviate most icing problems. Also, a heating
cable may be installed on exhaust piping and termination to
prevent freeze−ups. Heating cable installation kit is avail­able from Lennox. See Condensate Piping section for part
numbers.

IMPORTANT

Do not use screens or perforated metal in exhaust
terminations. Doing so will cause freeze−ups and
may block the terminations.

IMPORTANT

For Canadian Installations Only:
In accordance to CSA International B149 installation
codes, the minimum allowed distance between the
combustion air intake inlet and the exhaust outlet of
other appliances shall not be less than 12 inches
(305mm).

Page 26

FIGURE 29

VENT TERMINATION CLEARANCES

FOR NON−DIRECT VENT INSTALLATIONS IN THE USA AND CANADA

K

D

E

L

B

C

F

G

A

B

J

A

M

I

H

INSIDE CORNER

DETAIL

VENT TERMINAL

AIR SUPPLY INLET

AREA WHERE TERMINAL
IS NOT PERMITTED

Fixed

Closed

Operable

B

Fixed

Closed

Operable

B

B

A =

B =

C =

D =

E =

F =

G =

H =

I =

J =

K =

L =

M =

US Installations

1

Canadian Installations

2

12 inches (305mm) or 12 in. 305mm)

above average snow accumulation.

12 inches (305mm) or 12 in. 305mm)

above average snow accumulation.

Clearance above grade, veranda,

porch, deck or balcony

Clearance to window or

door that may be opened

4 feet (1.2 m) below or to side of opening;

1 foot (30 cm) above opening

6 inches (152mm) for appliances <10,000

Btuh (3kw), 12 inches (305mm) for

appliances > 10,000 Btuh (3kw) and

<100,000 Btuh (30kw), 36 inches (.9m)

for appliances > 100,000 Btuh (30kw)

Clearance to permanently

closed window

Vertical clearance to ventilated soffit

located above the terminal within a

horizontal distance of 2 feet (mm)

from the center line of the terminal

Clearance to unventilated soffit

Clearance to outside corner

Clearance to inside corner

Clearance to each side of center line ex-

tended above meter / regulator assembly

Clearance to service regulator

vent outlet

Clearance to non−mechanical air

supply inlet to building or the com-

bustion air inlet to any other ap-

pliance

Clearance to mechanical air sup-

ply inlet

Clearance above paved sidewalk or

paved driveway located on public property

Clearance under veranda, porch,

deck or balcony

* 12"

* Equal to or greater than soffit depth.

*

* 3 feet (.9m)

* 12"

3 feet (.9m) within a height 15 feet (4.5m)

above the meter / regulator assembly

3 feet (.9m)

6 inches (152mm) for appliances <10,000

Btuh (3kw), 12 inches (305mm) for

appliances > 10,000 Btuh (3kw) and

<100,000 Btuh (30kw), 36 inches (.9m)

for appliances > 100,000 Btuh (30kw)

3 feet (.9m) above if within 10 feet

(3m) horizontally

6 feet (1.8m)

7 feet (2.1m)

12 inches (305mm)

1

In accordance with the current ANSI Z223.1/NFPA 54 Natural Fuel Gas Code

2

In accordance with the current CSA B149.1, Natural Gas and Propane Installation Code

 A vent shall not terminate directly above a sidewalk or paved driveway that is located
between two single family dwellings and serves both dwellings.

 Permitted only if veranda, porch, deck or balcony is fully open on a minimum of two
sides beneath the floor. Lennox recommends avoiding this location if possible.

4 feet (1.2 m) below or to side of opening;

1 foot (30 cm) above opening

7 feet (2.1m)

* Equal to or greater than soffit depth.

* Equal to or greater than soffit depth.

* Equal to or greater than soffit depth.

* No minimum to outside corner * No minimum to outside corner

3 feet (.9m) within a height 15 feet (4.5m)

above the meter / regulator assembly

*12 inches (305mm)

**

*For clearances not specified in ANSI Z223.1/NFPA 54 or CSA B149.1,
clearance will be in accordance with local installation codes and the re­quirements of the gas supplier and these installation instructions."

Page 27

FIGURE 30

VENT TERMINATION CLEARANCES

FOR DIRECT VENT INSTALLATIONS IN THE USA AND CANADA

K

D

E

L

B

C

F

G

A

B

J

A

M

I

H

INSIDE CORNER

DETAIL

VENT TERMINAL

AIR SUPPLY INLET

AREA WHERE TERMINAL
IS NOT PERMITTED

Fixed

Closed

Operable

B

Fixed

Closed

Operable

B

B

A =

B =

C =

D =

E =

F =

G =

H =

I =

J =

K =

L =

M =

US Installations

1

Canadian Installations

2

12 inches (305mm) or 12 in. 305mm)

above average snow accumulation.

12 inches (305mm) or 12 in. 305mm)

above average snow accumulation.

Clearance above grade, veranda,

porch, deck or balcony

Clearance to window or

door that may be opened

6 inches (152mm) for appliances <10,000

Btuh (3kw), 9 inches (mm) for appliances

> 10,000 Btuh (3kw) and <50,000 Btuh

(15 kw), 12 inches (305mm) for ap-

pliances > 50,000 Btuh (15kw)

6 inches (152mm) for appliances <10,000

Btuh (3kw), 12 inches (305mm) for

appliances > 10,000 Btuh (3kw) and

<100,000 Btuh (30kw), 36 inches (.9m)

for appliances > 100,000 Btuh (30kw)

Clearance to permanently

closed window

Vertical clearance to ventilated soffit

located above the terminal within a

horizontal distance of 2 feet (mm)

from the center line of the terminal

Clearance to unventilated soffit

Clearance to outside corner

Clearance to inside corner

Clearance to each side of center line ex-

tended above meter / regulator assembly

Clearance to service regulator

vent outlet

Clearance to non−mechanical air

supply inlet to building or the com-

bustion air inlet to any other ap-

pliance

Clearance to mechanical air sup-

ply inlet

Clearance above paved sidewalk or

paved driveway located on public property

Clearance under veranda, porch,

deck or balcony

* 12"

*

*

* 7 feet (2.1m)

3 feet (.9m) within a height 15 feet (4.5m)

above the meter / regulator assembly

3 feet (.9m)

6 inches (152mm) for appliances <10,000

Btuh (3kw), 9 inches (mm) for appliances

> 10,000 Btuh (3kw) and <50,000 Btuh

(15 kw), 12 inches (305mm) for ap-

pliances > 50,000 Btuh (15kw)

6 inches (152mm) for appliances <10,000

Btuh (3kw), 12 inches (305mm) for

appliances > 10,000 Btuh (3kw) and

<100,000 Btuh (30kw), 36 inches (.9m)

for appliances > 100,000 Btuh (30kw)

3 feet (.9m) above if within 10 feet

(3m) horizontally

6 feet (1.8m)

7 feet (2.1m)

12 inches (305mm)

1

In accordance with the current ANSI Z223.1/NFPA 54 Natural Fuel Gas Code

2

In accordance with the current CSA B149.1, Natural Gas and Propane Installation Code

*For clearances not specified in ANSI Z223.1/NFPA 54 or CSA B149.1, clear­ance will be in accordance with local installation codes and the requirements
of the gas supplier and these installation instructions."

 A vent shall not terminate directly above a sidewalk or paved driveway that is located
between two single family dwellings and serves both dwellings.

 Permitted only if veranda, porch, deck or balcony is fully open on a minimum of two
sides beneath the floor. Lennox recommends avoiding this location if possible.

* 12"

* Equal to or greater than soffit depth

* Equal to or greater than soffit depth* Equal to or greater than soffit depth

* Equal to or greater than soffit depth * Equal to or greater than soffit depth

* No minimum to outside corner

* No minimum to outside corner

3 feet (.9m) within a height 15 feet (4.5m)

above the meter / regulator assembly

3 feet (.9m)

*

*12 inches (305mm)

Page 28

Details of Intake and Exhaust Piping Terminations for
Direct Vent Installation

NOTE − In Direct Vent installations, combustion air is tak­en from outdoors and flue gases are discharged to out­doors.

NOTE − Flue gas may be slightly acidic and may adversely
affect some building materials. If any vent termination is
used and the flue gasses may impinge on the building ma­terial, a corrosion−resistant shield (minimum 24 inches
square) should be used to protect the wall surface. If the
optional tee is used, the protective shield is recommended.
The shield should be constructed using wood, plastic,
sheet metal or other suitable material. All seams, joints,
cracks, etc. in the affected area should be sealed using an
appropriate sealant. See figure 35.

Intake and exhaust pipes may be routed either horizontally
through an outside wall or vertically through the roof. In attic
or closet installations, vertical termination through the roof
is preferred. Figures 31 through 43 show typical termina­tions.

1 − Exhaust and intake exits must be in same pressure

zone. Do not exit one through the roof and one on the
side. Also, do not exit the intake on one side and the
exhaust on another side of the house or structure.

2 − Intake and exhaust pipes should be placed as close

together as possible at termination end (refer to il­lustrations). Maximum separation is 3" (76mm) on roof
terminations and 6" (152mm) on side wall termina­tions.

3 − On roof terminations, the intake piping should termi-

nate straight down using two 90° elbows (See figure

31).

4 − Exhaust piping must terminate straight out or up as

shown. A reducer may be required on the exhaust pip­ing at the point where it exits the structure to improve
the velocity of exhaust away from the intake piping.
See table 8.

NOTE − Care must be taken to avoid recirculation of
exhaust back into intake pipe.

FIGURE 31

UNCONDITIONED

ATTIC SPACE

1/2" (13mm) FOAM

INSULATION IN

UNCONDITIONED

SPACE

SIZE TERMINATION

PIPE PER TABLE 8.

3"(76mm) MAX.

12" (305mm) ABOVE

AVERAGE SNOW
ACCUMULATION

3" (76mm) OR

2" (51mm) PVC

PROVIDE SUPPORT

FOR INTAKE AND

EXHAUST LINES

8" (203mm) MIN

Inches(mm)

DIRECT VENT ROOF TERMINATION KIT

(15F75 or 44J41)

FIGURE 32

FIELD SUPPLIED WALL TERMINATION OR

(15F74) WALL RING TERMINATION KIT

See venting table 7 for maximum venting lengths with this
arrangement.

* Use wall support every 24" (610 mm). Use two wall supports if
extension is greater than 24" (610 mm) but less than 48" (1219 mm).
NOTE − One wall support must be 6" (152 mm) from top of each pipe
(intake and exhaust)

2" (51mm)

Vent Pipe

3" (76mm)

Vent Pipe

A−Minimum clearance

above grade or average

snow accumulation

B−Maximum horizontal

separation between

intake and exhaust

C−Minimum from

end of exhaust to

inlet of intake

D−Maximum exhaust

pipe length

E−Maximum wall support

distance from top of each

pipe (intake/exhaust)

12" (508MM) 12" (508MM)

6" (152MM) 6" (152MM)

8" (203MM) 8" (203MM)

12" (305MM) 20" (508MM)

6" (152MM) 6" (152MM)

NOTE − FIELD PROVIDED

REDUCER MAY BE

REQUIRED TO ADAPT

LARGER VENT PIPE SIZE

TO TERMINATION

D

B

C

SIZE TERMINATION

PER TABLE 8

1/2" (13mm) ARMAFLEX

INSULATION IN UN-

CONDITIONED SPACE

STRAIGHT

APPPLICATION

B

C

A

D

* WALL

SUPPORT

1/2" (13mm) ARMAFLEX INSULATION

IN UNCONDITIONED SPACE

E

EXTENDED

APPLICATION

A

Page 29

FIGURE 33

FIELD SUPPLIED WALL TERMINATION OR

(15F74) WALL RING TERMINATION KIT

With INTAKE ELBOW

See venting table 7 for maximum venting lengths with this
arrangement.

* Use wall support every 24" (610 mm). Use two wall supports if
extension is greater than 24" (610 mm) but less than 48" (1219 mm).
NOTE − One wall support must be 6" (152 mm) from top of each pipe
(intake and exhaust)

2" (51mm)

Vent Pipe

3" (76mm)

Vent Pipe

12" (508MM) 12" (508MM)

6" (152MM) 6" (152MM)

6" (152MM)

12" (305MM) 20" (508MM)

6" (152MM) 6" (152MM)

6" (152MM)

A−Minimum clearance

above grade or average

snow accumulation

B−Maximum horizontal

separation between

intake and exhaust

C−Minimum from

end of exhaust to

inlet of intake

D−Maximum exhaust

pipe length

E−Maximum wall support

distance from top of each

pipe (intake/exhaust)

NOTE − FIELD PROVIDED

REDUCER MAY BE

REQUIRED TO ADAPT

LARGER VENT PIPE SIZE

TO TERMINATION

D

B

C

SIZE TERMINATION

PER TABLE 8

1/2" (13mm) ARMAFLEX

INSULATION IN UN-

CONDITIONED SPACE

STRAIGHT

APPPLICATION

B

C

D

* WALL

SUPPORT

1/2" (13mm) ARMAFLEX INSULATION

IN UNCONDITIONED SPACE

E

EXTENDED

APPLICATION

A

A

TABLE 8

EXHAUST PIPE TERMINATION SIZE REDUCTION

G61MPV

MODEL

Exhaust Pipe Size

Termination

Pipe Size

045, 070, 071

2" (51mm), 2−1/2" (64mm),

3" (76mm) or 4" (102mm)

1−1/2" (38mm)

090, 091 2" (51mm)
110, 111 2" (51mm)

135

3" (76mm) or 4" (102mm)

2" (51mm)

5 − On field supplied terminations for side wall exit, ex-

haust piping may extend a maximum of 12 inches
(305mm) for 2" PVC and 20 inches (508mm) for 3"
(76mm) PVC beyond the outside wall. Intake piping
should be as short as possible. See figures 32 and 33.

6 − On field supplied terminations, a minimum distance

between the end of the exhaust pipe and the end of
the intake pipe without a termination elbow is 8" and a
minimum distance of 6" with a termination elbow. See
figures 32 and 33.

7 − If intake and exhaust piping must be run up a side wall

to position above snow accumulation or other ob­structions, piping must be supported every 24"
(610mm) as shown in figures 32 and 33. In addition,
close coupled wall termination kits must be extended
for use in this application. See figures 41 and 42.
When exhaust and intake piping must be run up an
outside wall, the exhaust piping must be terminated
with pipe sized per table 8.The intake piping may be
equipped with a 90° elbow turndown. Using turndown
will add 5 feet (1.5m) to the equivalent length of the
pipe.

8 − Based on the recommendation of the manufacturer, a

multiple furnace installation may use a group of up to
four terminations assembled together horizontally, as
shown in figure 38.

FIGURE 34

2" EXTENSION FOR 2" PVC
PIPE1" EXTENSION FOR 3"
PVC PIPE

1−1/2" ACCELERATOR

(all −045, −070 and −090 units)

FURNACE
EXHAUST

PIPE

FURNACE

INTAKE

PIPE

4’’

GLUE EXHAUST

END FLUSH INTO

TERMINATION

FLAT
SIDE

FLUSH−MOUNT SIDE WALL TERMINATION

51W11

Page 30

C

A

E

D

B

A

B

D

D

B

C

A

C

12"

1

1

2

2

2" (51mm)

Vent Pipe

3" (76mm)

Vent Pipe

A− Clearance above

grade or average snow

accumulation

B−Horizontal

separation between

intake and exhaust

C−Minimum from

end of exhaust to

inlet of intake

D−Exhaust pipe length

E−Wall support distance

from top of each pipe

(intake/exhaust)

12" (508MM) Min.

12" (508MM) Min.

6" (152MM) Min.

24" (610 MM) Max

9" (227MM) Min.

12" (305MM) Min.
16" (405 MM) Max.

6" (152MM) Max.

6" (152MM) Min.

24" (610 MM) Max

9" (227MM) Min.

12" (305MM) Min.
20" (508MM) Max.

6" (152MM) Max.

TABLE 9

FIGURE 35

1

The exhaust termination tee should be connected to the 2" or 3" PVC flue pipe as shown in the illustration. Do

not use an accelerator in applications that include an exhaust termination tee. The accelerator is not required.

2

As required. Flue gas may be acidic and may adversely affect some building materials. If a side wall vent

termination is used and flue gases will impinge on the building materials, a corrosion−resistant shield (24 inches
square) should be used to protect the wall surface. If optional tee is used, the protective shield is recommende­d. The shield should be constructed using wood, sheet metal or other suitable material. All seams, joints,
cracks, etc. in affected area, should be sealed using an appropriate sealant.

3

Exhaust pipe 45° elbow can be rotated to the side away from the combustion air inlet to direct exhaust away

from adjacent property. The exhaust must never be directed toward the combustion air inlet.

Front View of

Intake and Exhaust

Intake

Exhaust

3

Intake

Exhaust

Page 31

FIGURE 36

DIRECT VENT CONCENTRIC ROOFTOP TERMINATION

71M80, 69M29 or 60L46 (US)

41W92 or 41W93 (Canada)

Minimum

Above Average

Snow

Accumulation

SHEET METAL STRAP

(Clamp and sheet metal strap
must be field installed to support
the weight of the termination kit.)

FLASHING

(Not Furnished)

CLAMP

FIELD−PROVIDED

REDUCER MAY BE REQUIRED

TO ADAPT LARGER VENT

PIPE SIZE TO TERMINATION

INTAKE

1 1/2" (38mm) accelerator

provided on 71M80 &

44W92 kits for

G61MPV−36B−045,

36B−070 & 36B−071

12” (305mm)

12" (305mm) Min.

above grade or

average snow ac-

cumulation.

FIGURE 37

DIRECT VENT CONCENTRIC WALL TERMINATION

71M80, 69M29 or 60L46 (US)

41W92 or 41W93 (Canada)

INTAKE

AIR

EXHAUST

AIR

INTAKE

AIR

INTAKE

AIR

EXHAUST

AIR

OUTSIDE

WALL

GRADE

CLAMP

(Not Furnished)

FIELD−PROVIDED

REDUCER MAY BE

REQUIRED TO ADAPT

LARGER VENT PIPE

SIZE TO TERMINATION

1 1/2" (38mm) accelerator

provided on 71M80 &

44W92 kits for

G61MPV−36B−045,

36B−070 & 36B−071

FIGURE 38

EXHAUST

VENT

INTAKE

AIR

5−1/2"

(140mm)

Front View

12"

(305mm)

5"

(127mm)

18" MAX.

(457mm)

EXHAUST VENT

INTAKE

AIR

OPTIONAL VENT TERMINATION FOR MULTIPLE UNIT

INSTALLATION OF DIRECT VENT WALL TERMINATION KIT

(22G44, 44J40, 30G28 or 81J20)

Inches (mm)

Side View

12" (305mm) Min.

above grade or

average snow ac-

cumulation.

optional intake elbow

FIGURE 39

1/2" (13mm) Foam Insulation

in Unconditioned Space

EXHAUST VENT

INTAKE AIR

OUTSIDE WALL

EXHAUST VENT

INTAKE

AIR

Front View

Top View

DIRECT VENT WALL TERMINATION KIT

(30G28 or 81J20)

6 (152mm) MIN.

SIZE

TERMINATION

PIPE PER

TABLE 8.

FIELD−PROVIDED

REDUCER MAY

BE REQUIRED TO

ADAPT LARGER

VENT PIPE SIZE

TO TERMINATION

FIGURE 40

1/2" (13mm) Foam Insulation

in Unconditioned Space

EXHAUST VENT

INTAKE AIR

OUTSIDE WALL

EXHAUST VENT

INTAKE

AIR

Front View

Top View

DIRECT VENT WALL TERMINATION KIT

(22G44 or 44J40)

8" (206mm) MIN.

SIZE

TERMINATION

PIPE PER

TABLE 8.

FIELD−PROVIDED

REDUCER MAY

BE REQUIRED TO

ADAPT LARGER

VENT PIPE SIZE

TO TERMINATION

Page 32

FIGURE 41

12” (305 mm) Minimum

Above Grade or Average

Snow Accumulation

1/2” (13 mm)

FOAM INSULATION

(Field Furnished)

5” (127 mm)

5−1/2”

(140 mm)

EXHAUST

AIR

INTAKE

AIR

GRADE

12”

(305 mm)

INTAKE

AIR

EXHAUST

AIR

GRADE

12” (305 mm) Max. for 2” (51 mm) Dia. Exhaust
20” (508 mm) Max. for 3” (76 mm) Dia. Exhaust

WALL SUPPORT*

12” (305 mm) Max. for 2” (51 mm) Dia. Exhaust
20” (508 mm) Max. for 3” (76 mm) Dia. Exhaust

12” (305 mm) Minimum

Above Grade or Average

Snow Accumulation

WALL TERMINATION KITS (CLOSE−COUPLE)

EXTENDED VENT FOR GRADE CLEARANCE

2 inch (51 mm) 22G44 (US)

3 inch (76 mm) 44J40 (US)

6” (152 mm)

Maximum

If Intake and Exhaust Pipe is less than 12 in. (305 mm)

above snow accumulation or other obstructions,
field fabricated piping must be installed.

8” (203 mm) Min. for 2” (51 mm) & 3” (76 mm) DIA. pipe

between the end of the exhaust pipe and intake pipe

8” (203 mm) Min.

*Use wall support every 24" (610). Use two supports if

extension is greater than 24" but less than 48".

FIELD−PROVIDED

REDUCER MAY BE REQUIRED TO ADAPT

LARGER VENT PIPE SIZE TO TERMINATION

FIGURE 42

12” (305 mm) Minimum

Above Grade or Average

Snow Accumulation

1/2” (13 mm)

FOAM INSULATION

(Field Furnished)

5” (127 mm)

5−1/2”

(140 mm)

EXHAUST

AIR

INTAKE

AIR

GRADE

12”

(305 mm)

INTAKE

AIR

EXHAUST

AIR

GRADE

WALL SUPPORT*

12” (305 mm) Minimum

Above Grade or Average

Snow Accumulation

WALL TERMINATION KITS (CLOSE−COUPLE)

EXTENDED VENT FOR GRADE CLEARANCE

2 inch (51 mm) 30G28 (WTK Canada)
3 inch (76 mm) 81J20 (WTK Canada)

See Installation Instructions for additional information.

6” (152 mm)

Maximum

If Intake and Exhaust Pipe is less than 12 in. (305 mm)
above snow accumulation or other obstructions,
field fabricated piping must be installed.

12” (305 mm) Max. for 2” (51 mm) Dia. Exhaust
20” (508 mm) Max. for 3” (76 mm) Dia. Exhaust

12” (305 mm) Max. for 2” (51 mm) Dia. Exhaust
20” (508 mm) Max. for 3” (76 mm) Dia. Exhaust

6” (152 mm)

Minimum

6” (152 mm)

Minimum

*Use wall support every 24" (610). Use two supports if

extension is greater than 24" but less than 48".

FIELD−PROVIDED

REDUCER MAY BE REQUIRED TO ADAPT

LARGER VENT PIPE SIZE TO TERMINATION

Page 33

G61MP DIRECT VENT APPLICATION

USING EXISTING CHIMNEY

NOTE − Do not discharge exhaust gases directly into any chimney or vent stack. If ver­tical discharge through an existing unused chimney or stack is required, insert piping
inside chimney until the pipe open end is above top of chimney and terminate as illus­trated. In any exterior portion of chimney, the exhaust vent must be insulated.

FIGURE 43

8" − 12"

(203mm − 305mm)

3" − 8"
(76mm−
203mm)

3" − 8"

(76mm−

203mm)

STRAIGHT−CUT OR

ANGLE−CUT IN DIRECTION

OF ROOF SLOPE *

EXHAUST VENT

1/2" (13mm)

WEATHERPROOF

INSULATION

SHOULDER OF FITTINGS

PROVIDE SUPPORT

OF PIPE ON TOP PLATE

ALTERNATE

INTAKE PIPE

INTAKE PIPE

INSULATION (optional)

EXTERIOR

PORTION OF

CHIMNEY

INSULATE
TO FORM

SEAL

SHEET

METAL TOP

PLATE

*SIZE TERMINATION

PIPE PER TABLE 8.

Minimum 12" (305MM)

above chimney top

plate or average snow

accumulation

Details of Exhaust Piping Terminations for Non-Direct
Vent Applications

Exhaust pipes may be routed either horizontally through an
outside wall or vertically through the roof. In attic or closet
installations, vertical termination through the roof is pre­ferred. Figures 44 through 47 show typical terminations.

1 − Exhaust piping must terminate straight out or up as

shown. The termination pipe must be sized as listed in
table 8.The specified pipe size ensures proper veloc­ity required to move the exhaust gases away from the
building.

2 − On field supplied terminations for side wall exit, ex-

haust piping may extend a maximum of 12 inches
(305mm) for 2" PVC and 20 inches (508mm) for 3"
(76mm) PVC beyond the outside wall. See figure 45.

FIGURE 44

NON−DIRECT VENT ROOF TERMINATION KIT

(15F75 or 44J41)

UNCONDITIONED

ATTIC SPACE

3" (76mm) OR

2" (51mm) PVC

PROVIDE SUPPORT

FOR EXHAUST LINES

12" (305mm)

ABOVE AVE.

SNOW

ACCUMULATION

SIZE TERMINATION
PIPE PER TABLE 8.

1/2" (13mm) FOAM

INSULATION

FIGURE 45

1/2" (13mm) ARMAFLEX

INSULATION IN

UNCONDITIONED SPACE

PVC REDUCER

1/2" (13mm)

ARMAFLEX

INSULATION

NON−DIRECT VENT FIELD SUPPLIED WALL TERMINATION OR

(15F74) WALL TERMINATION KIT

SIZE TERMINATION

PIPE PER TABLE 8.

FIELD−PROVIDED

REDUCER MAY

BE REQUIRED TO

ADAPT LARGER

VENT PIPE SIZE

TO TERMINATION

12" MIN.

(305mm)

Above Grade or

average snow
accumulation

12" (305mm) MAX. for 2" (51mm)
20" (508mm) MAX. for 3" (76mm)

3 − If exhaust piping must be run up a side wall to position

above snow accumulation or other obstructions, pip­ing must be supported every 24 inches (610mm) as
shown in figure 46. When exhaust piping must be run
up an outside wall, any reduction in exhaust pipe size
must be done after the final elbow.

Page 34

FIGURE 46

12" (305mm)

ABOVE GRADE OR

AVERAGE SNOW

ACCUMULATION

UNCONDITIONED

SPACE

1/2" (13mm) FOAM

INSULATION

1/2" (13mm) FOAM

INSULATION IN

UNCONDITIONED

SPACE

*WALL SUPPORT

OUTSIDE WALL

SIZE TER­MINATION

PIPE PER
TABLE 8.

FIELD−PROVIDED

REDUCER MAY BE

REQUIRED TO

ADAPT LARGER

VENT PIPE SIZE TO

TERMINATION

*Use wall support every 24" (610). Use two supports if extension is

greater than 24" but less than 48".

12" (305mm) MAX. for 2" (51mm)
20" (508mm) MAX. for 3" (76mm)

NON−DIRECT VENT FIELD SUPPLIED WALL TERMINATION

EXTENDED OR (15F74) WALL TERMINATION VENT PIPE

EXTENDED

6" (152mm)

Max

NOTE − Do not discharge exhaust gases directly into any chimney or vent stack. If ver­tical discharge through an existing unused chimney or stack is required, insert piping
inside chimney until the pipe open end is above top of chimney and terminate as illus­trated. In any exterior portion of chimney, the exhaust vent must be insulated.

FIGURE 47

3" − 8"
(76mm−
203mm)

3" − 8"

(76mm−

203mm)

STRAIGHT−CUT OR

ANGLE−CUT IN DIRECTION

OF ROOF SLOPE

EXHAUST VENT

1/2" (13mm)

WEATHERPROOF

INSULATION

SHOULDER OF FITTINGS

PROVIDE SUPPORT

OF PIPE ON TOP PLATE

EXTERIOR

PORTION OF

CHIMNEY

INSULATE

TO FORM

SEAL

SHEET

METAL TOP

PLATE

SIZE TERMINATION

PIPE PER TABLE 8.

G61MPV NON−DIRECT VENT APPLICATION

USING EXISTING CHIMNEY

Minimum 12" (305MM)

above chimney top

plate or average snow

accumulation

Condensate Piping

This unit is designed for either right- or left-side exit of con­densate piping in either upflow or downflow applications;
however, it must be installed on the same side of the unit as
the exhaust piping. In horizontal applications, the conden­sate trap should extend below the unit. A 5−1/2" service
clearance is required for the condensate trap. Refer to fig­ure 48 for condensate trap locations.

FIGURE 48

CONDENSATE TRAP LOCATIONS

(Unit shown in upflow position)

Horizontal

left and

optional

downflow

Horizontal

right and

optional

downflow

Optional

upflow

Optional

upflow

NOTE − In upflow applications where side return
air filter is installed on same side as the conden­sate trap, filter rack must be installed beyond
condensate trap to avoid interference.

1 − Determine which side condensate piping will exit the

unit. Remove plugs from the condensate collar at the
appropriate location on the side of the unit.

NOTE − The condensate trap is factory−shipped with
two rubber O−rings and two rubber clean−out caps
installed. Check to make sure that these items are in
place before installing the trap assembly.

2 − Install condensate trap onto the condensate collar.

Use provided HI/LO screws to secure two upper
flanges of the trap to the collar. Use provided sheet
metal screw to secure bottom trap flange to side of
unit. DO NOT apply glue to secure condensate trap
to cabinet. All other joints must be glued. See figure

49.

NOTE − In upflow and downflow applications, con­densate trap must be installed on the same side as
exhaust piping.

CAUTION

DO NOT use a power driver to tighten screws which
secure condensate trap to cabinet. Screws should
be hand−tightened using a screw driver to avoid the
possibility of damage to the trap assembly.

Page 35

3 − The condensate trap provided with the unit is

manufactured using ABS material. Use ABS to PVC
transition solvent cement to glue a field−provided PVC
coupling or PVC pipe to the trap. Install a tee and vent
pipe near the trap.

NOTE − The condensate trap drain stubs (both sides)
have an outer diameter which will accept a standard
3/4" PVC coupling. The inner diameter of each stub
will accept standard 1/2" diameter PVC pipe.

NOTE − Vinyl tubing may be used for condensate
drain. Tubing must be 1−1/4" OD X 1" ID and should be
attached to the drain stubs on the trap using a hose
clamp.

4 − Glue the field−provided drain line to the tee. Route the

drain line to an open drain. As an alternate, clear vinyl
tubing may be used to drain condensate away from
the trap. Secure the vinyl tubing to the drain stubs on
the trap using a hose clamp. Do not overtighten the
hose clamp.
Condensate line must be sloped downward away from
condensate trap to drain. If drain level is above con­densate trap, condensate pump must be used. Con­densate drain line should be routed within the condi­tioned space to avoid freezing of condensate and
blockage of drain line. If this is not possible, a heat
cable kit may be used on the condensate trap and line.
Heating cable kit is available from Lennox in various
lengths; 6 ft. (1.8m) − kit no. 26K68; 24 ft. (7.3m) − kit
no. 26K69; and 50 ft. (15.2m) − kit no. 26K70.

CAUTION

Do not use copper tubing or existing copper
condensate lines for drain line.

5 − If unit will be started immediately upon completion of

installation, prime trap per procedure outlined in Unit
Start−Up section.

6 − Glue the provided cap onto the unused condensate

drain line stub.

FIGURE 49

CONDENSATE ASSEMBLY

COUPLING

CAP

CONDENSATE TRAP

NIPPLE

NIPPLE

TEE

VENT

CLEAN−OUT ACCESS

(both sides)

HI/LO SCREWS
(DO NOT use power
driver. Hand−tighten
using screw driver.)

SCREW

O−RINGS

NOTE − Use screws to secure condensate trap to cabinet. DO
NOT apply glue to this joint. All other joints must be glued.

Page 36

Gas Piping

CAUTION

If a flexible gas connector is required or allowed by
the authority that has jurisdiction, black iron pipe
shall be installed at the gas valve and extend outside
the furnace cabinet.

WARNING

Do not exceed 600 in−lbs (50 ft−lbs) torque when at­taching the gas piping to the gas valve.

1 − Gas piping may be routed into the unit through either

the left- or right-hand side. Supply piping enters into
the gas valve from the side of the valve as shown in
figures 51 and 52.

2 − When connecting gas supply, factors such as length of

run, number of fittings and furnace rating must be con­sidered to avoid excessive pressure drop. Table 10
lists recommended pipe sizes for typical applications.

NOTE − Use two wrenches when connecting gas pip­ing to avoid transferring torque to the manifold.

3 − Gas piping must not run in or through air ducts, clothes

chutes, chimneys or gas vents, dumb waiters or eleva­tor shafts. Center gas line through piping hole. Gas
line should not touch side of unit. See figures 51 and

52.

4 − Piping should be sloped 1/4 inch per 15 feet (6mm per

5.6m) upward toward the gas meter from the furnace.
The piping must be supported at proper intervals, ev­ery 8 to 10 feet (2.44 to 3.05m), using suitable hangers
or straps. Install a drip leg in vertical pipe runs to serve as
a trap for sediment or condensate.

5 − A 1/8" N.P.T. plugged tap or pressure post is located

on the gas valve to facilitate test gauge connection.
See figures 59 and 60.

6 − In some localities, codes may require installation of a

manual main shut-off valve and union (furnished by in­staller) external to the unit. Union must be of the
ground joint type.

IMPORTANT

Compounds used on threaded joints of gas piping
must be resistant to the actions of liquified petro­leum gases.

FIGURE 50

MANUAL MAIN SHUT−OFF

VALVE WILL NOT HOLD

NORMAL TEST PRESSURE

CAP

FURNACE

ISOLATE

GAS VALVE

1/8 NPT PLUG

Leak Check

After gas piping is completed, carefully check all piping
connections (factory− and field−installed) for gas leaks. Use
a leak detecting solution or other preferred means.

The furnace must be isolated from the gas supply system
by closing its individual manual shut-off valve during any
pressure testing of the gas supply system at pressures less
than or equal to 1/2 psig (3.48 kPa, 14 inches w.c.).

IMPORTANT

When testing gas lines using pressures in excess of
1/2 psig (3.48 kPa), gas valve must be disconnected
and isolated. See figure 50. Gas valves can be dam­aged if subjected to pressures greater than 1/2 psig
(3.48 kPa).

WARNING

FIRE OR EXPLOSION HAZARD
Failure to follow the safety warnings exactly could
result in serious injury, death, or property damage.
Never use an open flame to test for gas leaks. Check
all connections using a commercially available soap
solution made specifically for leak detection.Some
soaps used for leak detection are corrosive to certain
metals. Carefully rinse piping thoroughly after leak
test has been completed.

GROUND

JOINT

UNION

AUTOMATIC

GAS VALVE
(with manual

shut−off valve)

FIELD

PROVIDED

AND INSTALLED

Upflow Application

Left Side Piping

(Standard)

DRIP LEG

MANUAL

MAIN SHUT−OFF

VALV E

GROUND

JOINT

UNION

DRIP LEG

MANUAL

MAIN SHUT−OFF

VALV E

Upflow Application

Right Side Piping

(Alternate)

FIGURE 51

Page 37

GROUND

JOINT
UNION

DRIP LEG

MANUAL

MAIN SHUT−OFF

VALV E

GROUND

JOINT

UNION

DRIP LEG

MANUAL

MAIN SHUT−OFF

VALV E

GROUND

JOINT
UNION

DRIP LEG

MANUAL

MAIN SHUT−OFF

VALV E

Horizontal Applications

Possible Gas Piping Configurations

Horizontal Application

Left−Side Air Discharge

Horizontal Application

Right−Side Air Discharge

FIGURE 52

TABLE 10

GAS PIPE CAPACITY − FT3/HR (kL/HR)

Nominal

Iron Pipe Size

−Inches(mm)

Internal

Diameter

−Inches(mm)

Length of Pipe−Feet(m)

10

(3.048)20(6.096)30(9.144)40(12.192)50(15.240)60(18.288)70(21.336)80(24.384)90(27.432)

100

(30.480)

1/4

(6.35)

.364

(9.246)

43

(1.13)

29

(.82)

24

(.68)

20

(.57)

18

(.51)

16

(.45)

15

(.42)

14

(.40)

13

(.37)

12

(.34)

3/8

(9.53)

.493

(12.522)

95

(2.69)

65

(1.84)

52

(1.47)

45

(1.27)

40

(1.13)

36

(1.02)

33

(.73)

31

(.88)

29

(.82)

27

(.76)

1/2

(12.7)

.622

(17.799)

175

(4.96)

120

(3.40)

97

(2.75)

82

(2.32)

73

(2.07)

66

(1.87)

61

(1.73)

57

(1.61)

53

(1.50)

50

(1.42)

3/4

(19.05)

.824

(20.930)

360

(10.19)

250

(7.08)

200

(5.66)

170

(4.81)

151

(4.28)

138

(3.91)

125

(3.54)

118

(3.34)

110

(3.11)

103

(2.92)

1

(25.4)

1.049

(26.645)

680

(19.25)

465

(13.17)

375

(10.62)

320

(9.06)

285

(8.07)

260

(7.36)

240

(6.80)

220

(6.23)

205

(5.80)

195

(5.52)

1−1/4

(31.75)

1.380

(35.052)

1400

(39.64)

950

(26.90)

770

(21.80)

660

(18.69)

580

(16.42)

530

(15.01)

490

(13.87)

460

(13.03)

430

(12.18)

400

(11.33)

1−1/2

(38.1)

1.610

(40.894)

2100

(59.46)

460

(41.34)

1180

(33.41)

990

(28.03)

900

(25.48)

810

(22.94)

750

(21.24)

690

(19.54)

650

(18.41)

620

(17.56)

2

(50.8)

2.067

(52.502)

3950

(111.85)

2750

(77.87)

2200

(62.30)

1900

(53.80)

1680

(47.57)

1520

(43.04)

1400

(39.64)

1300

(36.81)

1220

(34.55)

1150

(32.56)

2−1/2

(63.5)

2.469

(67.713)

6300

(178.39)

4350

(123.17)

3520

(99.67)

3000

(84.95)

2650

(75.04)

2400

(67.96)

2250

(63.71)

2050

(58.05)

1950

(55.22)

1850

(52.38)

3

(76.2)

3.068

(77.927)

11000

(311.48)

7700

(218.03)

6250

(176.98)

5300

(150.07)

4750

(134.50)

4300

(121.76)

3900

(110.43)

3700

(104.77)

3450

(97.69)

3250

(92.03)

4

(101.6)

4.026

(102.260)

23000

(651.27)

15800

(447.39)

12800

(362.44)

10900

(308.64)

9700

(274.67)

8800

(249.18)

8100

(229.36)

7500

(212.37)

7200

(203.88)

6700

(189.72)

NOTE − Capacity given in cubic feet of gas per hour (kilo liters of gas per hour) and based on 0.60 specific gravity gas.

Page 38

Electrical

ELECTROSTATIC DISCHARGE (ESD)

Precautions and Procedures

CAUTION

Electrostatic discharge can affect electronic
components. Take precautions during furnace
installation and service to protect the furnace’s
electronic controls. Precautions will help to avoid
control exposure to electrostatic discharge by putt­ing the furnace, the control and the technician at the
same electrostatic potential. Neutralize electrostat­ic charge by touching hand and all tools on an un­painted unit surface, such as the gas valve or blower
deck, before performing any service procedure.

INTERIOR MAKE−UP BOX INSTALLATION

MAKE−UP

BOX

Right Side

FIGURE 53

INTERIOR MAKE−UP BOX INSTALLATION

MAKE−UP

BOX

Left side

FIGURE 54

The unit is equipped with a field make−up box. The make−
up box may be moved to the right side of the furnace to fa­cilitate installation. If the make−up box is moved to the right
side, the excess wire must be pulled into the blower
compartment. Secure the excess wire to the existing harn­ess to protect it from damage.

Refer to figure 55 and table 11 for field wiring and figure 58
for schematic wiring diagram and troubleshooting.

1 − The power supply wiring must meet Class I restric-

tions. Protected by either a fuse or circuit breaker, se­lect circuit protection and wire size according to unit
nameplate.

NOTE − Unit nameplate states maximum current draw.
Maximum Over−Current Protection allowed is 20AMP.

2 − Holes are on both sides of the furnace cabinet to facili-

tate wiring.

3 − Install a separate (properly sized) disconnect switch

near the furnace so that power can be turned off for
servicing.

4 − Before connecting the thermostat or the power wiring,

check to make sure the wires will be long enough for
servicing at a later date. Remove the blower access
panel to check the length of the wire.

5 − Complete the wiring connections to the equipment.

Use the provided unit wiring diagram and the field wir­ing diagram shown in figure 55 and table 11. Use
18−gauge wire or larger that is suitable for Class II ra­ting for thermostat connections.

NOTE − Do NOT make a wire connection between
the room thermostat L terminal and the L terminal
of the G61MPV integrated control.

6 − Electrically ground the unit according to local codes or,

in the absence of local codes, according to the current
National Electric Code (ANSI/NFPA No. 70) for the
USA and current Canadian Electric Code part 1 (CSA
standard C22.1) for Canada. A green ground wire is
provided in the field make−up box.

NOTE − The G61MPV furnace contains electronic
components that are polarity sensitive. Make sure that
the furnace is wired correctly and is properly grounded.

7 − One line voltage EAC" 1/4" spade terminal is provided

on the furnace control board. Any electronic air cleaner
rated up to one amp can be connected to this terminal
with the neutral leg of the circuit being connected to
one of the provided neutral terminals. See figure 56 for
control board configuration. This terminal is energized
when the indoor blower is operating.

8 − One line voltage HUM" 1/4" spade terminal is provided

on the furnace control board. Any humidifier rated up
to one amp can be connected to this terminal with the
neutral leg of the circuit being connected to one of the

Page 39

provided neutral terminals. See figure 56 for control
board configuration. This terminal is energized in the
heating mode when the combustion air inducer is oper­ating.

9 − One 24V H" terminal is provided on the furnace control

board terminal block. Any humidifier rated up to 0.5
amp can be connected to this terminal with the ground
leg of the circuit being connected to either ground or
the C" terminal. See figure 56 for control board config­uration.

10 −Install the room thermostat according to the instruc-

tions provided with the thermostat. See table 11 for
thermostat connections. If the furnace is being

matched with a heat pump, refer to the instruction
packaged with the dual fuel thermostat.

Indoor Blower Speeds

1 − When the thermostat is set to FAN ON," the indoor

blower will run continuously at approximately 38% of
the second−stage cooling speed when there is no cool­ing or heating demand.

2 − When the G61MPV is running in the heating mode, the

indoor blower will run on the heating speed designated
by the positions of DIP switches 11 and 12.

3 − When there is a cooling demand, the indoor blower will

run on the cooling speed designated by the positions
of DIP switches 5 and 6.

TYPICAL G61MPV FIELD WIRING DIAGRAM

FIGURE 55

FIELD INSTALLED CLASS II 24V
FIELD INSTALLED LINE VOLTAGE

USE COPPER CONDUCTORS ONLY.

Page 40

TABLE 11

Field Wiring Applications

Thermostat

Dip Switch Settings and On Board Links (See figure 56)

Wiring Connections

DIP Switch 1

W915

Two−Stage

Cooling

W914 Dehu­midification
or Harmony

IIIt

W951

Heat Pumps

1Heat / 1 Cool

NOTE − Use DIP
switch 2 to set
second−stage
heat ON delay.
OFF−10 minutes.
ON−15 minutes.

ON Intact Intact Intact

S1

T’STAT

CONTROL

TERM. STRIP

OUTDOOR

UNIT

EXISTING

W915 JUMPER

1 Heat / 2 Cool

NOTE − Use DIP
switch 2 to set
second−stage
heat ON delay.
OFF−10 minutes.
ON−15 minutes.

ON Cut Intact Intact

S1

T’STAT

CONTROL

TERM. STRIP

OUTDOOR

UNIT

1 Heat / 2 Cool
with t’stat with
humidity control

NOTE − Use DIP
switch 2 to set
second−stage
heat ON delay.
OFF−10 minutes.
ON−15 minutes.

ON Cut Cut Intact

S1

T’STAT

CONTROL

TERM. STRIP

OUTDOOR

UNIT

Page 41

TABLE 11

Field Wiring Applications (Continued)

Thermostat

Dip Switch Settings and On Board Links (See figure 56)

Wiring Connections

DIP Switch 1

W915

Two−Stage

Cooling

W914 Dehu­midification
or Harmony

IIIt

W951

Heat Pumps

2 Heat / 2 Cool OFF Cut Intact Intact

S1

T’STAT

CONTROL

TERM. STRIP

OUTDOOR

UNIT

2 Heat / 2 Cool
with t’stat with
humidity control

OFF Cut Cut Intact

S1

T’STAT

CONTROL

TERM. STRIP

OUTDOOR

UNIT

2 Heat / 1 Cool OFF Intact Intact Intact

S1

T’STAT

CONTROL

TERM. STRIP

OUTDOOR

UNIT

EXISTING

W915 JUMPER

Page 42

TWO−STAGE, VARIABLE SPEED INTEGRATED CONTROL BOARD

FIGURE 56

THERMOSTAT CONNECTIONS (TB1)

1/4" QUICK CONNECT TERMINALS

DIP SWITCH FUNCTIONS

INDOOR

BLOWER DIP

SWITCHES

HEATING

DIP

SWITCHES

LEDs

ON−BOARD

JUMPERS

H= 24V HUMIDIFIER OUTPUT
L= DO NOT USE
1= FUTURE USE

NEUTRALS= 120 VAC NEUTRAL

W914

W951

W915

HTG DIP SWITCH(ES) FUNCTION

5 and 6 Cooling Mode Blower Speed
7 and 8 Blower Speed Adjustment

9 and 10 Cooling Mode Blower Ramping Profile

11 and 12 Heating Mode Blower Speed

1 T’stat Heat Stages (single or two−stage)
2 Second Stage ON Delay (single−stage t’stat)

3 and 4 Heating Fan OFF Delay

INDOOR BLOWER

DIP SWITCH(ES)

FUNCTION

1 − 4

FUTURE USE

Page 43

INTEGRATED CONTROL BOARD DIP SWITCH SETTINGS AND JUMPERS

FIGURE 57

Page 44

TYPICAL G61MPV WIRING DIAGRAM

FIGURE 58

Page 45

Integrated Control Board

G61MPV units are equipped with a two−stage, variable
speed integrated control. This control manages ignition
timing, heating mode fan off delays and indoor blower
speeds based on selections made using the control dip
switches and jumpers. The control includes an internal
watchguard feature which automatically resets the ignition
control when it has been locked out. After one hour of con­tinuous thermostat demand for heat, the watchguard will
break and remake thermostat demand to the furnace and
automatically reset the control to relight the furnace.

Heating Operation DIP Switch Settings −− Figure 57

Switch 1 −− Thermostat Selection −− This unit may be used

with either a single−stage or two−stage thermostat. The
thermostat selection is made using a DIP switch which
must be properly positioned for the particular application.
The DIP switch is factory−positioned for use with a two−
stage thermostat. If a single−stage thermostat is to be used,
the DIP switch must be repositioned.

a − Select OFF" for two−stage heating operation con-

trolled by a two−stage heating thermostat (factory set­ting);

b − Select ON" for two−stage heating operation con-

trolled by a single−stage heating thermostat. This set­ting provides a timed delay before second−stage heat
is initiated.

Switch 2 −− Second Stage Delay (Used with Single−
Stage Thermostat Only) −− This switch is used to deter-

mine the second stage on delay when a single−stage ther­mostat is being used. The switch is factory−set in the OFF
position, which provides a 10−minute delay before second−
stage heat is initiated. If the switch is toggled to the ON
position, it will provide a 15−minute delay before second−
stage heat is initiated. This switch is only activated when
the thermostat selector jumper is positioned for SINGLE−
stage thermostat use.

Switches 3 and 4 −− Blower−Off Delay −− The blower−on
delay of 45 seconds is not adjustable. The blower−off delay
(time that the blower operates after the heating demand
has been satisfied) can be adjusted by moving switches 3
and 4 on the integrated control board. The unit is shipped
from the factory with a blower−off delay of 90 seconds. The
blower off delay affects comfort and is adjustable to satisfy
individual applications. Adjust the blower off delay to
achieve a supply air temperature between 90° and 110°F at
the exact moment that the blower is de−energized. Longer
off delay settings provide lower supply air temperatures;
shorter settings provide higher supply air temperatu­res.Table 12 provides the blower off timings that will result
from different switch settings.

TABLE 12

Blower Off Delay Switch Settings

Blower Off Delay

(Seconds)

Switch 3 Switch 4

60 Off On

90 Off Off
120 On Off
180 On On

Indoor Blower Operation DIP Switch Settings

−− Figure 57
Switches 5 and 6 −− Cooling Mode Blower Speed −−

Switches 5 and 6 are used to select cooling blower motor
speed. The unit is shipped from the factory with the DIP
switches positioned for high speed (4) indoor blower motor
operation during the cooling mode. The table below pro­vides the cooling mode blower speeds that will result from
different switch settings. Refer to tables 17 through 28 for
corresponding cfm values.

TABLE 13

Cooling Mode Blower Speeds

Speed

Switch 5 Switch 6

1 − Low On On

2 − Medium Low Off On

3 − Medium High On Off

4 − High (Factory) Off Off

Switches 7 and 8 −− Blower Speed Adjustment −−

Switches 7 and 8 are used to select blower speed adjust­ment settings. The unit is shipped from the factory with the
DIP switches positioned for NORMAL (no) adjustment.
The DIP switches may be positioned to adjust the blower
speed by +10% or −10% to better suit the application. The
table below provides blower speed adjustments that will re­sult from different switch settings. Refer to tables 17
through 28 for corresponding cfm values.

TABLE 14

Blower Speed Adjustment

Adjustment

Switch 7 Switch 8

+10% (approx.) On Off

NORMAL (Factory) Off Off

−10% (approx.) Off On

Switches 9 and 10 −− Cooling Mode Blower Speed
Ramping −− Switches 9 and 10 are used to select cooling

mode blower speed ramping options. Blower speed ramp­ing may be used to enhance dehumidification perfor­mance. The switches are factory set at option A which has
the greatest effect on blower motor performance. Table 15
provides the cooling mode blower speed ramping options
that will result from different switch settings. The cooling
mode blower speed ramping options are detailed on the
next page.

NOTE − The off portion of the selected ramp profile only ap­plies during heat pump operation in dual fuel applications.

Page 46

TABLE 15

Cooling Mode Blower Speed Ramping

Ramping Option

Switch 9 Switch 10

A (Factory) Off Off

B On Off
C Off On
D On On

Ramping Option A (Factory Selection)

D Motor runs at 50% for 30 seconds.
D Motor then runs at 82% for approximately 7−1/2 minu-

tes.

D If demand has not been satisfied after 7−1/2 minutes,

motor runs at 100% until demand is satisfied.

D Once demand is met, motor runs at 50% for 30 sec-

onds then ramps down to stop.

OFF

OFF

1/2 MIN
50% CFM

COOLING DEMAND

7 1/2 MIN
82% CFM

100%
CFM

1/2 MIN
50% CFM

Ramping Option B

S Motor runs at 82% for approximately 7−1/2 minutes. If

demand has not been satisfied after 7−1/2 minutes,
motor runs at 100% until demand is satisfied.

S Once demand is met, motor ramps down to stop.

OFF

OFF

82%CFM

100% CFM

COOLING DEMAND

7 1/2 MIN

Ramping Option C

S Motor runs at 100% until demand is satisfied.

S Once demand is met, motor runs at 100% for 45 sec-

onds then ramps down to stop.

OFF

OFF

100% CFM

100% CFM

DEMAND

45 SEC.

Ramping Option D

S Motor runs at 100% until demand is satisfied.

S Once demand is met, motor ramps down to stop.

OFFOFF

100% CFM

COOLING
DEMAND

Switches 11 and 12 −− Heating Mode Blower Speed −−

Switches 11 and 12 are used to select heating mode blower
motor speed. The unit is shipped from the factory with the
dip switches positioned for medium low (2) speed indoor
blower motor operation during the heating mode. The table
below provides the heating mode blower speeds that will
result from different switch settings. Refer to tables 17
through 28 for corresponding cfm values.

TABLE 16

Heating Mode Blower Speeds

Speed

Switch 11 Switch 12

1 − Low On On

2 − Medium Low

(Factory)

Off On

3 − Medium High On Off

4 − High Off Off

On−Board Jumper W914 −− Figure 57

On−board jumper W914, which connects terminals DS and
R on the integrated control board, must be cut when the fur­nace is installed with either the Harmony IIIt zone control
board or a thermostat which features humidity control. If
the jumper is left intact the PMW signal from the Harmony
III control will be blocked and also lead to control damage.
Refer to table 29 for operation sequence in applications in­cluding G61MPV, a thermostat which features humidity
control and a single−speed outdoor unit. Table 30 gives the
operation sequence in applications with a two−speed out­door unit.

On−Board Jumper W951 −− Figure 57

On−board jumper W951, which connects terminals R and O
on the integrated control board, must be cut when the fur­nace is installed in applications which include a heat pump
unit and a thermostat which features dual fuel use. If the
jumper is left intact, terminal O" will remain energized elim­inating the HEAT MODE in the heat pump.

On−Board Jumper W915 −− Figure 57

On−board jumper W915, which connects terminals Y1 and
Y2 on the integrated control board, must be cut if two−stage
cooling will be used. If the jumper is not cut the outdoor unit
will operate in second−stage cooling only.

LEDs (SPEED, CFM, STATUS, E−COM) −− Figure 56

The green SPEED LED indicates circulating blower speed
in response to the DS signal. The LED is lit during normal
blower operation and is off during a dehumidification de­mand. In Harmony III applications, the brightness of the
LED indicates the requested blower speed.

The green CFM LED indicates the blower air flow. Count
the number of blinks between the two−second pauses to
determine the CFM. Each blink represents approximately
100 CFM.

The STATUS LED flashes diagnostic codes, which are de­tailed on page 43.

The green E−COM LED indicates that the control is receiv­ing and processing commands and inputs. The LED may
flash rapidly or may display a single flash, depending upon
the activity.

Page 47

TABLE 17

G61MPV−36B−045 BLOWER MOTOR PERFORMANCE (LESS FILTER)

0.0" to 0.8" w.g. (0 through 200 Pa) External Static Pressure Range

Factory Settings: Heating Speed − 2; Cooling Speed − 4; Speed Adjust − NORM

ADJUST"

Switch

Positions

Speed Switch Positions

Second Stage HEAT" Speed Second Stage COOL" Speed

1 2 3 4 1 2 3 4

cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s

+

915 430 1070 505 1320 625 1370 645 1055 500 1235 580 1330 625 1420 670

NORM 830 395 965 455 1205 570 1255 590 945 445 100 520 1185 560 1295 610

 740

350 860 405 1055 500 1095 515 840 395 970 460 1050 495 1150 540

ADJUST"

Switch

Positions

First Stage HEAT" Speed First Stage COOL" Speed

1 2 3 4 1 2 3 4

cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s

+

830 390 970 460 1210 570 1255 590 720 340 820 385 890 420 970 455

NORM 755 355 880 415 1080 510 1120 530 665 310 745 350 795 375 875 410



690 325 795 375 950 450 995 470 610 290 685 325 725 340 785 370

N/A − First and second stage HEAT positions shown cannot be used on this model.
NOTES − The effect of static pressure is included in air volumes shown.

First stage HEAT is approximately 91% of the same second stage

HEAT speed position.

First stage COOL (two−stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan Only speed is approximately 38% of the same second stage COOL speed position − minimum 500 cfm (235 L/s).
Lennox Harmony IIIt Zone Control Applications − Minimum blower speed is 442 cfm (210 L/s).

TABLE 18

G61MPV−36B−070 and G61MPV−36B−071 BLOWER MOTOR PERFORMANCE (LESS FILTER)

0.0" to 0.8" w.g. (0 through 200 Pa) External Static Pressure Range

Factory Settings: Heating Speed − 2; Cooling Speed − 4; Speed Adjust − NORM

ADJUST"

Switch

Positions

Speed Switch Positions

Second Stage HEAT" Speed Second Stage COOL" Speed

1 2 3 4 1 2 3 4

cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s

+

895 420 1025 485 1290 610 1340 630 1015 480 1190 560 1280 605 1395 660

NORM 820 385 940 445 1155 545 1210 570 930 440 1065 505 1155 545 1270 600

 N/A

N/A 840 395 1020 480 1055 495 830 390 950 450 1010 475 1105 520

ADJUST"

Switch

Positions

First Stage HEAT" Speed First Stage COOL" Speed

1 2 3 4 1 2 3 4

cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s

+

820 385 930 440 1160 550 1210 570 730 345 815 385 865 410 935 440

NORM 760 360 865 410 1045 495 1090 515 680 320 755 355 795 375 855 405



N/A N/A 775 365 930 440 965 455 625 295 695 330 730 345 775 365

N/A − First and second stage HEAT positions shown cannot be used on this model.
NOTES − The effect of static pressure is included in air volumes shown.

First stage HEAT is approximately 91% of the same second stage

HEAT speed position.

First stage COOL (two−stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan Only speed is approximately 38% of the same second stage COOL speed position − minimum 500 cfm (235 L/s).
Lennox Harmony IIIt Zone Control Applications − Minimum blower speed is 458 cfm (215 L/s).

Page 48

TABLE 19

G61MPV−36C−090 BLOWER MOTOR PERFORMANCE (LESS FILTER)

0.0" to 0.8" w.g. (0 through 200 Pa) External Static Pressure Range

Factory Settings: Heating Speed − 2; Cooling Speed − 4; Speed Adjust − NORM

ADJUST"

Switch

Positions

Speed Switch Positions

Second Stage HEAT" Speed Second Stage COOL" Speed

1 2 3 4 1 2 3 4

cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s

+

N/A N/A 1040 490 1285 605 1340 630 1020 480 1185 560 1275 600 1395 660

NORM N/A N/A 915 430 1150 540 1200 565 905 430 1060 500 1145 540 1270 600

 N/A

N/A N/A N/A 1020 480 1055 495 800 380 925 435 1010 475 1100 520

ADJUST"

Switch

Positions

First Stage HEAT" Speed First Stage COOL" Speed

1 2 3 4 1 2 3 4

cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s

+

N/A N/A 940 445 1160 550 1210 570 705 335 790 375 845 400 920 435

NORM N/A N/A 840 395 1040 490 1075 510 650 305 730 345 770 365 830 395



N/A N/A N/A N/A 915 430 945 445 600 285 670 315 705 330 750 355

N/A − First and second stage HEAT positions shown cannot be used on this model.
NOTES − The effect of static pressure is included in air volumes shown.

First stage HEAT is approximately 91% of the same second stage

HEAT speed position.

First stage COOL (two−stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan Only speed is approximately 38% of the same second stage COOL speed position − minimum 500 cfm (235 L/s).
Lennox Harmony IIIt Zone Control Applications − Minimum blower speed is 479 cfm (225 L/s).

TABLE 20

G61MPV−60C−090 and G61MPV−60C−091 BLOWER MOTOR PERFORMANCE (LESS FILTER)

0.0" to 0.8" w.g. (0 through 200 Pa) External Static Pressure Range

Factory Settings: Heating Speed − 2; Cooling Speed − 4; Speed Adjust − NORM.

Return Air Options: Bottom; both sides; or bottom and one side.

ADJUST"

Switch

Positions

Speed Switch Positions

Second Stage HEAT" Speed Second Stage COOL" Speed

1 2 3 4 1 2 3 4

cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s

+

1500 710 1675 790 1880 885 2090 985 1605 760 1710 805 1925 910 2165 1020

NORM 1355 640 1545 730 1720 810 1900 895 1440 680 1560 735 1755 825 1960 925

 1194

565 1365 645 1540 730 1695 800 1275 600 1380 650 1590 750 1755 830

ADJUST"

Switch

Positions

First Stage HEAT" Speed First Stage COOL" Speed

1 2 3 4 1 2 3 4

cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s

+

1360 640 1560 735 1730 815 1910 900 1105 520 1185 560 1355 640 1545 730

NORM 1220 575 1405 665 1585 750 1740 820 995 470 1080 510 1205 570 1345 635



1105 520 1235 585 1410 665 1570 740 890 420 960 455 1090 515 1215 575

NOTES − The effect of static pressure is included in air volumes shown.

First stage HEAT is approximately 91% of the same second stage

HEAT speed position.

First stage COOL (two−stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan Only speed is approximately 38% of the same second stage COOL speed position − minimum 500 cfm (235 L/s).
Lennox Harmony IIIt Zone Control Applications − Minimum blower speed is 449 cfm (210 L/s).

Page 49

TABLE 21

G61MPV−60C−090 and G61MPV−60C−091 BLOWER MOTOR PERFORMANCE (LESS FILTER)

0.0" to 0.8" w.g. (0 through 200 Pa) External Static Pressure Range

Factory Settings: Heating Speed − 2; Cooling Speed − 4; Speed Adjust − NORM.

Return Air Options: Single side return air − Bold volumes require field−fabricated transition to accommodate

20 x 25 x 1 in. (508 x 635 x 25 mm) cleanable air filter in order to maintain proper air velocity across the filter.

ADJUST"

Switch

Positions

Speed Switch Positions

Second Stage HEAT" Speed Second Stage COOL" Speed

1 2 3 4 1 2 3 4

cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s

+

1450 685 1640 775 1820 860 2055 970 1575 745 1690 795 1895 895 2135 1005

NORM 1320 625 1510 710 1700 800 1870 880 1405 665 1530 720 1735 820 1935 910

 1165

550 1320 625 1500 705 1665 785 1250 590 1355 640 1560 735 1735 820

ADJUST"

Switch

Positions

First Stage HEAT" Speed First Stage COOL" Speed

1 2 3 4 1 2 3 4

cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s

+

1315 620 1510 715 1695 800 1875 885 1080 510 1160 545 1315 620 1490 705

NORM 1190 560 1365 645 1545 730 1715 810 985 465 1060 500 1185 560 1330 625



1075 510 1205 570 1370 645 1520 715 865 410 930 440 1065 500 1185 560

NOTES − The effect of static pressure is included in air volumes shown.

First stage HEAT is approximately 91% of the same second stage

HEAT speed position.

First stage COOL (two−stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan Only speed is approximately 38% of the same second stage COOL speed position − minimum 500 cfm (235 L/s).
Lennox Harmony IIIt Zone Control Applications − Minimum blower speed is 449 cfm (210 L/s).

TABLE 22

G61MPV−60C−090 and G61MPV−60C−091 BLOWER MOTOR PERFORMANCE (LESS FILTER)

0.0" to 0.8" w.g. (0 through 200 Pa) External Static Pressure Range

Factory Settings: Heating Speed − 2; Cooling Speed − 4; Speed Adjust − NORM.

Return Air Options: Single side return with optional RAB return air base

ADJUST"

Switch

Positions

Speed Switch Positions

Second Stage HEAT" Speed Second Stage COOL" Speed

1 2 3 4 1 2 3 4

cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s

+

1440 680 1630 770 1810 855 2015 950 1525 720 1655 780 1860 880 2100 990

NORM 1300 615 1485 700 1655 780 1830 865 1385 655 1500 710 1695 800 1905 900

 1155

545 1310 620 1480 700 1640 775 1240 585 1320 625 1510 710 1695 800

ADJUST"

Switch

Positions

First Stage HEAT" Speed First Stage COOL" Speed

1 2 3 4 1 2 3 4

cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s

+

1320 625 1490 700 1665 785 1840 870 1060 500 1135 535 1285 605 1455 685

NORM 1180 555 1345 635 1515 715 1680 795 960 455 1035 490 1165 550 1310 620



1055 500 1180 560 1340 630 1490 705 865 405 920 435 1050 495 1165 550

NOTES − The effect of static pressure is included in air volumes shown.

First stage HEAT is approximately 91% of the same second stage

HEAT speed position.

First stage COOL (two−stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan Only speed is approximately 38% of the same second stage COOL speed position − minimum 500 cfm (235 L/s).
Lennox Harmony IIIt Zone Control Applications − Minimum blower speed is 449 cfm (210 L/s).

Page 50

TABLE 23

G61MPV−60C−110 and G61MPV−60C−111 BLOWER MOTOR PERFORMANCE (LESS FILTER)

0.0" to 0.8" w.g. (0 through 200 Pa) External Static Pressure Range

Factory Settings: Heating Speed − 2; Cooling Speed − 4; Speed Adjust − NORM.

Return Air Options: Bottom; both sides; or bottom and one side.

ADJUST"

Switch

Positions

Speed Switch Positions

Second Stage HEAT" Speed Second Stage COOL" Speed

1 2 3 4 1 2 3 4

cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s

+

1505 710 1710 805 1915 905 2130 1005 1625 770 1745 825 1990 940 2210 1045

NORM 1370 645 1565 740 1765 835 1945 920 1465 690 1580 745 1790 845 1995 940

 1205

570 1380 650 1565 740 1740 820 1290 610 1405 660 1605 760 1790 845

ADJUST"

Switch

Positions

First Stage HEAT" Speed First Stage COOL" Speed

1 2 3 4 1 2 3 4

cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s

+

1370 645 1570 740 1760 830 1945 920 945 445 1020 480 1160 545 1300 615

NORM 1235 585 1420 670 1600 755 1780 840 840 395 910 430 1055 500 1180 555



1105 525 1250 590 1420 670 1580 745 740 350 800 380 920 435 1045 495

NOTES − The effect of static pressure is included in air volumes shown.

First stage HEAT is approximately 91% of the same second stage

HEAT speed position.

First stage COOL (two−stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan Only speed is approximately 38% of the same second stage COOL speed position − minimum 500 cfm (235 L/s).
Lennox Harmony IIIt Zone Control Applications − Minimum blower speed is 463 cfm (220 L/s).

TABLE 24

G61MPV−60C−110 and G61MPV−60C−111 BLOWER MOTOR PERFORMANCE (LESS FILTER)

0.0" to 0.8" w.g. (0 through 200 Pa) External Static Pressure Range

Factory Settings: Heating Speed − 2; Cooling Speed − 4; Speed Adjust − NORM.

Return Air Options: Single side return air − Bold volumes require field−fabricated transition to accommodate

20 x 25 x 1 in. (508 x 635 x 25 mm) cleanable air filter in order to maintain proper air velocity across the filter.

ADJUST"

Switch

Positions

Speed Switch Positions

Second Stage HEAT" Speed Second Stage COOL" Speed

1 2 3 4 1 2 3 4

cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s

+

1485 700 1675 790 1870 885 2080 980 1585 750 1700 800 1905 900 2135 1005

NORM 1350 637 1525 720 1725 815 1895 895 1435 680 1535 725 1740 820 1930 910

 1175

555 1335 630 1505 710 1670 790 1280 605 1385 655 1570 740 1755 830

ADJUST"

Switch

Positions

First Stage HEAT" Speed First Stage COOL" Speed

1 2 3 4 1 2 3 4

cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s

+

1325 625 1505 710 1695 800 1870 885 935 440 1025 485 1155 545 1285 605

NORM 1195 565 1365 645 1550 730 1720 810 840 395 915 430 1050 495 1175 555



1080 510 1205 570 1365 645 1530 720 750 355 800 380 925 435 1050 495

NOTES − The effect of static pressure is included in air volumes shown.

First stage HEAT is approximately 91% of the same second stage

HEAT speed position.

First stage COOL (two−stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan Only speed is approximately 38% of the same second stage COOL speed position − minimum 500 cfm (235 L/s).
Lennox Harmony IIIt Zone Control Applications − Minimum blower speed is 463 cfm (220 L/s).

Page 51

TABLE 25

G61MPV−60C−110 and G61MPV−60C−111 BLOWER MOTOR PERFORMANCE (LESS FILTER)

0.0" to 0.8" w.g. (0 through 200 Pa) External Static Pressure Range

Factory Settings: Heating Speed − 2; Cooling Speed − 4; Speed Adjust − NORM.

Return Air Options: Single side return air with optional RAB return base. −

20 x 25 x 1 in. (508 x 635 x 25 mm) cleanable air filter in order to maintain proper air velocity across the filter.

ADJUST"

Switch

Positions

Speed Switch Positions

Second Stage HEAT" Speed Second Stage COOL" Speed

1 2 3 4 1 2 3 4

cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s

+

1475 695 1670 790 1865 880 2070 980 1555 735 1685 795 1895 895 2130 1005

NORM 1345 635 1500 710 1695 800 1865 880 1415 670 1540 725 1735 820 1930 910

 1180

555 1345 635 1510 710 1685 795 1245 590 1350 635 1545 730 1725 815

ADJUST"

Switch

Positions

First Stage HEAT" Speed First Stage COOL" Speed

1 2 3 4 1 2 3 4

cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s

+

1330 625 1510 715 1695 800 1875 885 1085 510 1155 545 1310 620 1475 695

NORM 1195 565 1375 650 1550 730 1725 815 955 450 1050 495 1185 560 1335 630



1080 510 1210 570 1370 645 1520 715 850 400 920 435 1070 505 1195 565

NOTES − The effect of static pressure is included in air volumes shown.

First stage HEAT is approximately 91% of the same second stage

HEAT speed position.

First stage COOL (two−stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan Only speed is approximately 38% of the same second stage COOL speed position − minimum 500 cfm (235 L/s).
Lennox Harmony IIIt Zone Control Applications − Minimum blower speed is 463 cfm (220 L/s).

TABLE 26

G61MPV−60D−135 BLOWER MOTOR PERFORMANCE (LESS FILTER)

0.0" to 0.8" w.g. (0 through 200 Pa) External Static Pressure Range

Factory Settings: Heating Speed − 2; Cooling Speed − 4; Speed Adjust − NORM.

Return Air Options: Bottom; both sides; or bottom and one side.

ADJUST"

Switch

Positions

Speed Switch Positions

Second Stage HEAT" Speed Second Stage COOL" Speed

1 2 3 4 1 2 3 4

cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s

+

1505 710 1705 805 1900 900 2110 995 1615 760 1730 815 1945 920 2190 1035

NORM 1365 645 1550 730 1740 820 1920 905 1455 685 1580 745 1780 840 1985 935

 1225

580 1380 650 1545 730 1720 810 1305 615 1400 660 1600 755 1780 840

ADJUST"

Switch

Positions

First Stage HEAT" Speed First Stage COOL" Speed

1 2 3 4 1 2 3 4

cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s

+

1385 655 1570 740 1760 830 1930 910 1135 535 1205 570 1365 645 1540 725

NORM 1250 590 1425 670 1595 755 1775 835 1025 485 1105 520 1235 580 1390 655



1135 535 1265 595 1430 675 1585 750 915 430 985 465 1115 525 1235 585

NOTES − The effect of static pressure is included in air volumes shown.

First stage HEAT is approximately 91% of the same second stage

HEAT speed position.

First stage COOL (two−stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan Only speed is approximately 38% of the same second stage COOL speed position − minimum 500 cfm (235 L/s).
Lennox Harmony IIIt Zone Control Applications − Minimum blower speed is 470 cfm (210 L/s).

Page 52

TABLE 27

G61MPV−60D−135 BLOWER MOTOR PERFORMANCE (LESS FILTER)

0.0" to 0.8" w.g. (0 through 200 Pa) External Static Pressure Range

Factory Settings: Heating Speed − 2; Cooling Speed − 4; Speed Adjust − NORM.

Return Air Options: Single side return air − Bold volumes require field−fabricated transition to accommodate

20 x 25 x 1 in. (508 x 635 x 25 mm) cleanable air filter in order to maintain proper air velocity across the filter.

ADJUST"

Switch

Positions

Speed Switch Positions

Second Stage HEAT" Speed Second Stage COOL" Speed

1 2 3 4 1 2 3 4

cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s

+

1470 695 1650 780 1845 870 2040 965 1585 750 1705 805 1905 900 2130 1005

NORM 1325 625 1495 705 1680 795 1865 880 1430 675 1545 730 1765 835 1975 930

 N/A

N/A 1335 630 1505 710 1670 790 1275 600 1370 645 1565 740 1755 830

ADJUST"

Switch

Positions

First Stage HEAT" Speed First Stage COOL" Speed

1 2 3 4 1 2 3 4

cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s

+

1335 630 1510 710 1695 800 1870 885 1105 520 1180 555 1330 630 1500 710

NORM 1210 570 1370 645 1540 725 1710 810 990 465 1075 505 1210 570 1355 640



N/A N/A 1225 575 1375 650 1515 715 890 420 950 450 1085 515 1210 570

N/A − First and second stage HEAT positions shown cannot be used on this model.
NOTES − The effect of static pressure is included in air volumes shown.

First stage HEAT is approximately 91% of the same second stage

HEAT speed position.

First stage COOL (two−stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan Only speed is approximately 38% of the same second stage COOL speed position − minimum 500 cfm (235 L/s).
Lennox Harmony IIIt Zone Control Applications − Minimum blower speed is 470 cfm (220 L/s).

TABLE 28

G61MPV−60D−135 BLOWER MOTOR PERFORMANCE (LESS FILTER)

0.0" to 0.8" w.g. (0 through 200 Pa) External Static Pressure Range

Factory Settings: Heating Speed − 2; Cooling Speed − 4; Speed Adjust − NORM.

Return Air Options: Single side return air with optional RAB return air base

20 x 25 x 1 in. (508 x 635 x 25 mm) cleanable air filter in order to maintain proper air velocity across the filter.

ADJUST"

Switch

Positions

Speed Switch Positions

Second Stage HEAT" Speed Second Stage COOL" Speed

1 2 3 4 1 2 3 4

cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s

+

1445 685 1635 770 1825 860 2025 955 1550 730 1660 785 1875 885 2105 995

NORM 1305 615 1475 695 1660 785 1840 870 1400 660 1510 715 1720 810 1920 905

 N/A

N/A 1315 620 1480 700 1650 780 1250 590 1345 635 1530 725 1715 810

ADJUST"

Switch

Positions

First Stage HEAT" Speed First Stage COOL" Speed

1 2 3 4 1 2 3 4

cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s

+

1315 620 1490 705 1675 790 1855 875 1080 510 1155 545 1310 620 1478 695

NORM 1195 565 1365 645 1530 725 1695 800 985 465 1055 500 1190 560 1325 625



N/A N/A 1210 570 1360 640 1500 710 875 410 945 445 1060 500 1190 560

N/A − First and second stage HEAT positions shown cannot be used on this model.
NOTES − The effect of static pressure is included in air volumes shown.

First stage HEAT is approximately 91% of the same second stage

HEAT speed position.

First stage COOL (two−stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan Only speed is approximately 38% of the same second stage COOL speed position − minimum 500 cfm (235 L/s).
Lennox Harmony IIIt Zone Control Applications − Minimum blower speed is 470 cfm (220 L/s).

Page 53

TABLE 29

OPERATING SEQUENCE

G61MPV, SignatureStattThermostat and Single−Stage Outdoor Unit

OPERATING

SEQUENCE

SYSTEM DEMAND SYSTEM RESPONSE

System

Condition

Step

Thermostat Demand Relative Humidity

Compressor

Blower

CFM

(COOL)

Comments

Y1 O G

W

1

Status D

NO CALL FOR DEHUMIDIFICATION

Normal Operation 1 On On On Acceptable

24

VAC

High 100%

Compressor and indoor
blower follow thermostat
demand

BASIC MODE (only active on a Y1 thermostat demand)

Normal Operation 1 On On On Acceptable

24

VAC

High 100%

SignatureStatt thermo-
stat energizes Y1 and de−
energizes D on a call for
de−humidification

Dehumidification

Call

2 On On On Demand

0

VAC

High 70%

PRECISION MODE (operates independent of a Y1 thermostat demand)

Normal Operation 1 On On On Acceptable

24

VAC

High 100%

Dehumidification mode
begins when humidity is
greater than set point

Dehumidification

call

2 On On On Demand

0

VAC

High 70%

Dehumidification

call ONLY

1 On On On Demand

0

VAC

High 70%

SignatureStatt thermo-
stat will keep outdoor unit
energized after cooling
temperature setpoint has
been reached in order to
maintain room humidity
setpoint.*

Jumpers at indoor unit with a single stage outdoor unit
With Condensing unit − Cut W914 (R to DS) on SureLight

®

board

With Heat Pump − Cut W914 (R to DS) & W951 (R to O) on SureLight

®

board

*In Precision mode, SignatureStatt thermostat will allow room temperatures up to 2 °F (1.2°C) cooler than room setting.

Page 54

TABLE 30

OPERATING SEQUENCE

G61MPV, SignatureStattThermostat and Two−Stage Outdoor Unit

OPERATING

SEQUENCE

SYSTEM DEMAND SYSTEM RESPONSE

System

Condition

Step

Thermostat Demand Relative Humidity

Compressor

Blower

CFM

(COOL)

Comments

Y1 Y2 O G

W1W

2

Status D

NO CALL FOR DEHUMIDIFICATION

Normal Operation −

Y1

1 On On On Acceptable

24

VAC

Low 70%

Compressor and indoor
blower follow thermostat
demand

Normal Operation −

Y2

2 On On On On Acceptable

24

VAC

High 100%

ROOM THERMOSTAT CALLS FOR FIRST STAGE COOLING

BASIC MODE (only active on a Y1 thermostat demand)

Normal Operation 1 On On On Acceptable

24

VAC

Low 70%

SignatureStatt thermostat
energizes Y2 and de−ener­gizes D on a call for de−hu­midification

Dehumidification

Call

2 On On On On Demand

0

VAC

High 70%

PRECISION MODE (operates independent of a Y1 thermostat demand)

Normal Operation 1 On On On Acceptable

24

VAC

Low 70%

Dehumidification mode be­gins when humidity is
greater than set point

Dehumidification

call

2 On On On On Demand

0

VAC

High 70%

Dehumidification

call ONLY

1 On On On On Demand

0

VAC

High 70%

SignatureStatt thermostat
will keep outdoor unit en­ergized after cooling tem­perature setpoint has been
reached in order to main­tain room humidity set­point.*

ROOM THERMOSTAT CALLS FOR FIRST AND SECOND STAGE COOLING

BASIC MODE (only active on a Y1 thermostat demand)

Normal Operation 1 On On On On Acceptable

24

VAC

High 100%

SignatureStatt thermostat
energizes Y2 and de−ener­gizes D on a call for de−hu­midification

Dehumidification

Call

2 On On On On Demand

0

VAC

High 70%

PRECISION MODE (operates independent of a Y1 thermostat demand)

Normal Operation 1 On On On Acceptable

24

VAC

Low 70%

Dehumidification mode be­gins when humidity is
greater than set point

Dehumidification

call

2 On On On On Demand

0

VAC

High 70%

Dehumidification

call ONLY

1 On On On On Demand

0

VAC

High 70%

SignatureStatt thermostat
will keep outdoor unit en­ergized after cooling tem­perature setpoint has been
reached in order to main­tain room humidity set­point.*

Jumpers at indoor unit with a two stage outdoor unit
Cut factory jumper from Y1 to Y2 or cut W915 (Y1 to Y2) on SureLight

®

board

With Condensing unit − Cut W914 (R to DS) on SureLight

®

board

With Heat Pump − Cut W914 (R to DS) & W951 (R to O) on SureLight

®

board

*In Precision mode, SignatureStatt thermostat will allow room temperature up to 2 °F (1.2°C) cooler than room setting.

Page 55

Unit Start−Up

FOR YOUR SAFETY READ BEFORE OPERATING

WARNING

Do not use this furnace if any part has been
underwater. A flood−damaged furnace is extremely
dangerous. Attempts to use the furnace can result
in fire or explosion. Immediately call a qualified ser­vice technician to inspect the furnace and to replace
all gas controls, control system parts, and electrical
parts that have been wet or to replace the furnace,
if deemed necessary.

WARNING

Danger of explosion. Can cause injury
or product or property damage. Should
the gas supply fail to shut off or if
overheating occurs, shut off the gas
valve to the furnace before shutting off
the electrical supply.

CAUTION

Before attempting to perform any service or mainte­nance, turn the electrical power to unit OFF at dis­connect switch.

Priming Condensate Trap

The condensate trap should be primed with water prior to
start−up to ensure proper condensate drainage. Either
pour 10 fl. oz. (300 ml) of water into the trap, or follow
these steps to prime the trap:

1 − Follow the lighting instructions to place the unit into op-

eration.

2 − Set the thermostat to initiate a heating demand.

3 − Allow the burners to fire for approximately 3 minutes.
4 − Adjust the thermostat to deactivate the heating de-

mand.

5 − Wait for the combustion air inducer to stop. Set the

thermostat to initiate a heating demand and again al­low the burners to fire for approximately 3 minutes.

6 − Adjust the thermostat to deactivate the heating de-

mand and again wait for the combustion air inducer to
stop. At this point, the trap should be primed with suffi­cient water to ensure proper condensate drain opera­tion.

BEFORE LIGHTING the unit, smell all around the fur­nace area for gas. Be sure to smell next to the floor be­cause some gas is heavier than air and will settle on the
floor.

The gas valve on the G61MPV is equipped with a gas
control switch (lever). Use only your hand to turn the gas
control switch. Never use tools. If the the switch will not
move by hand, do not try to repair it. Force or attempted
repair may result in a fire or explosion.

Placing the furnace into operation:

G61MPV units are equipped with an automatic ignition
system. Do not

attempt to manually light burners on this
furnace. Each time the thermostat calls for heat, the
burners will automatically light. The ignitor does not get
hot when there is no call for heat on units with this ignition
system.

WARNING

If you do not follow these instructions exactly, a fire
or explosion may result causing property damage,
personal injury or death.

Gas Valve Operation (Figures 59 and 60)

1 − STOP! Read the safety information at the beginning of

this section.

2 − Set the thermostat to the lowest setting.

3 − Turn off all electrical power to the unit.
4 − This furnace is equipped with an ignition device which

automatically lights the burners. Do not try to light the

burners by hand.
5 − Remove the upper access panel.
6 − White Rodgers 36E Gas Valve − Move gas valve

switch to OFF. See figure 59 for the White Rodgers

36E valve.

Honeywell VR8205 Gas Valve − Turn switch on gas

valve clockwise

to OFF. Do not force. See figure

60.

7 − Wait five minutes to clear out any gas. If you then smell

gas, STOP! Immediately call your gas supplier from a

neighbor’s phone. Follow the gas supplier’s instruc-

tions. If you do not smell gas go to next step.

WHITE RODGERS 36E SERIES GAS VALVE

GAS VALVE SHOWN IN OFF POSITION

HIGH FIRE

MANIFOLD

PRESSURE

ADJUSTMENT

ON SIDE

(under cap)

MANIFOLD

PRESSURE

TAP ON SIDE

INLET PRESSURE

TAP ON SIDE

LOW FIRE MANIFOLD

PRESSURE ADJUSTMENT

ON SIDE (under cap)

FIGURE 59

Page 56

HONEYWELL VR8205 SERIES GAS VALVE

GAS VALVE SHOWN IN OFF POSITION

MANIFOLD

PRESSURE

TAP

HIGH FIRE

ADJUSTING SCREW

(under cap)

INLET PRESSURE TAP

LOW FIRE

ADJUSTING SCREW

(under cap)

FIGURE 60

8 − White Rodgers 36E Gas Valve − Move gas valve switch

to ON. See figure 59 for the White Rodgers 36E
valve.
Honeywell VR8205 Gas Valve − Turn switch on gas

valve counterclockwise

to ON. Do not force.

9 − Replace the upper access panel.

10− Turn on all electrical power to to the unit.

11− Set the thermostat to desired setting.

NOTE − When unit is initially started, steps 1 through 11
may need to be repeated to purge air from gas line.

12− If the appliance will not operate, follow the instructions

Turning Off Gas to Unit" and call the gas supplier.

Turning Off Gas to Unit

1 − Set the thermostat to the lowest setting.
2 − Turn off all electrical power to the unit if service is to be

performed.
3 − Remove the upper access panel.
4 − White Rodgers 36E Gas Valve − Move switch on gas

valve to OFF.

Honeywell VR8205 Gas Valve − Turn switch on gas

valve clockwise

to OFF. Do not force.

5 − Replace the upper access panel.

Gas Pressure Adjustment

Gas Flow (Approximate)

1 − Operate unit at least 15 minutes before checking gas

flow. Determine the time in seconds for one revolu­tions of gas through the meter. A portable LP gas me­ter (17Y44) is available for LP applications.

2 − Compare the number of seconds and the gas meter

size in table 31 to determine the gas flow rate. Multiply
the gas flow rate by the heating value to determine the
unit input rate. If manifold pressure is correct and the
unit input rate is incorrect, check gas orifices for proper
size and restriction.

3 − Remove temporary gas meter if installed.

NOTE − To obtain accurate reading, shut off all other gas
appliances connected to meter.

TABLE 31

Gas Flow Rate (Ft.

3

/Hr.)

Seconds for 1

Revolution

Gas Meter Size

1/2 cu ft Dial 1 cu ft Dial

10 180 360
12 150 300
14 129 257
16 113 225
18 100 200
20 90 180
22 82 164
24 75 150
26 69 138
28 64 129
30 60 120
32 56 11 3
34 53 106
36 50 100
38 47 95
40 45 90
42 43 86
44 41 82
46 39 78
48 38 75
50 36 72
52 35 69
54 33 67
56 32 64
58 31 62
60 30 60

Page 57

Manifold Pressure Measurement & Adjustment

Supply Pressure Measurement

A threaded plug on the inlet side of the gas valve provides
access to the supply pressure tap. Remove the threaded
plug, install a field−provided barbed fitting and connect a
manometer to measure supply pressure. Replace the
threaded plug after measurements have been taken.

Manifold Pressure Measurement

To correctly measure manifold pressure, the differential
pressure between the positive gas manifold and the nega­tive burner box must be considered. Use pressure test

adapter kit (available as Lennox part 10L34) to assist in
measurement.

1 − Remove the threaded plug from the outlet side of the

gas valve and install a field−provided barbed fitting.
Connect test gauge +" connection to barbed fitting to
measure manifold pressure.

2 − Tee into the gas valve regulator vent hose and connect

test gauge −" connection.

3 − Start unit on low heat (68% rate) and allow 5 minutes

for unit to reach steady state.

4 − While waiting for the unit to stabilize, notice the flame.

Flame should be stable and should not lift from burner.
Natural gas should burn blue.

5 − After allowing unit to stabilize for 5 minutes, record

manifold pressure and compare to value given in table

32.

6 − Repeat steps 3, 4 and 5 on high heat.

NOTE − Shut unit off and remove manometer as soon as an
accurate reading has been obtained. Take care to remove
barbed fitting and replace threaded plug.

CAUTION

Do not attempt to make adjustments to the gas valve.

TABLE 32

Manifold Pressure (Outlet)

Model Number

Fuel

Altitude (feet)

0−2000 2001−4500 4501−5500 5501−6500 6501−7500 7501−10000

Low
Fire

High
Fire

Low
Fire

High
Fiire

Low
Fire

High
Fiire

Low
Fire

High
Fiire

Low
Fire

High
Fiire

Low
Fire

High
Fiire

045, 070, 071, 090,
110, 135

Natural 1.7 3.5 1.7 3.5 1.7 3.5 1.7 3.5 1.7 3.5 1.7 3.5

Propane 4.9 10.0 4.9 10.0 4.9 10.0 4.9 10.0 4.9 10.0 4.9 10.0

091, 111

Natural 1.7 3.5 1.7 3.4 1.7 3.3 1.7 3.2 1.7 3.1 1.7 3.5

Propane 4.9 10.0 4.9 10.0 4.9 10.0 4.9 10.0 4.9 10.0 4.9 10.0

High Altitude Information

NOTE − In Canada, certification for installations at eleva­tions over 4500 feet (1372 m) is the jurisdiction of local au­thorities.

The manifold pressure may require adjustment to ensure
proper operation at higher altitudes. Refer to table 32 for
manifold pressure and table 33 for required pressure

switch changes and conversion kits at varying altitudes.

The combustion air pressure switches are factory−set and
require no adjustment.

NOTE − A natural to L.P. propane gas changeover kit is nec­essary to convert this unit. Refer to the changeover kit
installation instruction for the conversion procedure.

TABLE 33

Conversion Kit Requirements

Input

High Altitude

Orifice Kit

Natural Gas

Only

High Altitude Pressure Switch Kit

ORDER TWO EACH

LPG/Propane Kit LPG/Propane to

Natural Gas Kit

7501−10,000 ft. 2000−4500 ft. 4501−7500 ft. 7501−10,000 ft. 0−7500 ft. 7501−10,000 ft. 0−7500 ft.

1

7501−10,000 ft.

−045 44W51 − − − − − − − − − 44W48 44W50 44W49 44W49 + 44W51

−070 44W51 − − − − − − 56M23 44W48 44W50 44W49 44W49 + 44W51

−071 44W51 75M22 75M22 56M21 44W48 44W50 44W49 44W49 + 44W51

−090 44W51 − − − 75M22 56M21 44W48 44W50 44W49 44W49 + 44W51

−091 47M82 26W85 26W85 26W86 44W48 44W50 44W49 44W49 + 47M82

−110 44W51 − − − 56M23 75M22 44W48 44W50 44W49 44W49 + 44W51

−111 47M82 56M22 56M22 56M23 44W48 44W50 44W49 44W49 + 47M82

−135 44W51 − − − 56M93 56M93 44W48 44W50 44W49 44W49 + 44W51

1

High Altitude Orifice Kit is required and must be ordered separately for applications from 7501 to 10,000 ft.

Page 58

Testing for Proper Venting and Sufficient Combustion Air for Non−Direct Vent Applications

WARNING

CARBON MONOXIDE POISONING HAZARD!

Failure to follow the steps outlined below for each
appliance connected to the venting system being
placed into operation could result in carbon monox­ide poisoning or death.
The following steps shall be followed for each ap­pliance connected to the venting system being
placed into operation, while all other appliances con­nected to the venting system are not in operation.

After the G61MPV gas furnace has been started, the fol­lowing test should be conducted to ensure proper venting
and sufficient combustion air has been provided to the
G61MPV, as well as to other gas-fired appliances which
are separately vented.

If a G61MPV furnace replaces a Category I furnace which
was commonly vented with another gas appliance, the size
of the existing vent pipe for that gas appliance must be
checked. Without the heat of the original furnace flue prod­ucts, the existing vent pipe is probably oversized for the
single water heater or other appliance. The vent should be
checked for proper draw with the remaining appliance.

The test should be conducted while all appliances (both in
operation and those not in operation) are connected to the
venting system being tested. If the venting system has
been installed improperly, or if provisions have not been
made for sufficient amounts of combustion air, corrections
must be made as outlined in the previous section.

1 − Seal any unused openings in the venting system.

2 − Visually inspect the venting system for proper size and

horizontal pitch. Determine there is no blockage or re­striction, leakage, corrosion, or other deficiencies
which could cause an unsafe condition.

3 − To the extent that it is practical, close all building doors

and windows and all doors between the space in which
the appliances connected to the venting system are lo-

cated and other spaces of the building.
4 − Close fireplace dampers.
5 − Turn on clothes dryers and any appliances not con-

nected to the venting system. Turn on any exhaust

fans, such as range hoods and bathroom exhausts, so

they will operate at maximum speed. Do not operate a

summer exhaust fan.
6 − Follow the lighting instruction to place the appliance

being inspected into operation. Adjust thermostat so

appliance will operate continuously.
7 − Use the flame of match or candle to test for spillage of

flue gases at the draft hood relief opening after 5 min-

utes of main burner operation.
8 − If improper venting is observed during any of the

above tests, the venting system must be corrected or

sufficient combustion/make-up air must be provided.

The venting system should be re-sized to approach

the minimum size as determined by using the ap-

propriate tables in appendix G in the current standards

of the National Fuel Gas Code ANSI−Z223.1/NPFA 54

in the U.S.A., and the appropriate Natural Gas and

Propane appliances venting sizing tables in the cur-

rent standard of the CSA−B149 Natural Gas and Pro-

pane Installation Codes in Canada.
9 − After determining that each appliance remaining

connected to the common venting system properly

vents when tested as indicated in step 3, return

doors, windows, exhaust fans, fireplace dampers

and any other gas-burning appliance to their previous

condition of use.

Page 59

Other Unit Adjustments

Primary and Secondary Limits

The primary limit is located on the heating compartment
vestibule panel. The secondary limits are located in the
blower compartment, attached to the back side of the blow­er. These limits are factory set and require no adjustment.

Flame Rollout Switches (Two)

These manually reset switches are located on the burner
box. If tripped, check for adequate combustion air before
resetting.

Pressure Switches (Two or Four)

The pressure switches are located in the heating compart­ment on the combustion air inducer. These switches check
for proper combustion air inducer operation before allow­ing ignition trial. The switches are factory−set and require
no adjustment.

Back−Up Secondary Limit (090, 091, 110, 111 & 135)

The back−up secondary limit is located on the combustion
air inducer. This switch protects the plastic components
from overheating due to indoor blower motor failure. If
tripped, check for proper blower operation before resetting.

Temperature Rise

After the furnace has been started and supply and return air
temperatures have been allowed to stabilize, check the
temperature rise. If necessary, adjust the blower speed to
maintain the temperature rise within the range shown on
the unit nameplate. Increase the blower speed to decrease
the temperature. Decrease the blower speed to increase
the temperature rise. Failure to adjust the temperature rise
may cause erratic limit operation.

Thermostat Heat Anticipation

Set the heat anticipator setting (if adjustable) according to
the amp draw listed on the wiring diagram that is attached
to the unit.

Electrical

1 − Check all wiring for loose connections.
2 − Check for the correct voltage at the furnace (furnace

operating).

3 − Check amp-draw on the blower motor.

Motor Nameplate__________Actual__________

NOTE − Do not secure the electrical conduit directly to the
air ducts or structure.

Electronic Ignition

The integrated control has an added feature of an internal
Watchguard control. The feature serves as an automatic re­set device for ignition control lockout caused by ignition fail­ure. This type of lockout is usually due to low gas line pres­sure. After one hour of continuous thermostat demand for
heat, the Watchguard will break and remake thermostat de­mand to the furnace and automatically reset the control to
begin the ignition sequence.

Exhaust and Air Intake Pipe

1 − Check exhaust and air intake connections for tightness

and to make sure there is no blockage.

2 − Are pressure switches closed? Obstructed exhaust

pipe will cause unit to shut off at pressure switches.
Check termination for blockages.

3 − Reset manual flame rollout switches on burner box

cover.

Failure To Operate

If the unit fails to operate, check the following:
1 − Is the thermostat calling for heat?
2 − Are access panels securely in place?
3 − Is the main disconnect switch closed?
4 − Is there a blown fuse?
5 − Is the filter dirty or plugged? Dirty or plugged filters will

cause the limit control to shut the unit off.
6 − Is gas turned on at the meter?
7 − Is the manual main shut-off valve open?
8 − Is the internal manual shut-off valve open?
9 − Is the unit ignition system in lock out? If the unit locks out

again,inspect the unit for blockages.

Heating Sequence of Operation

NOTE − The thermostat selection DIP switchon the control
board is factory−set in the TWO−STAGE" position.

Applications Using a Two−Stage Thermostat

A − Heating Sequence −− Control Board Thermostat
Selection DIP switch in Two−Stage" Position (Factory
Setting)

1 − On a call for heat, thermostat first−stage contacts close

sending a signal to the integrated control. The inte­grated control runs a self-diagnostic program and
checks high temperature limit switches for normally
closed contacts and pressure switches for normally
open contacts.The combustion air inducer is ener­gized at low speed and the humidifier terminal is ener­gized.

2 − Once the control receives a signal that the low−fire

pressure switch has closed, the combustion air induc­er begins a 15−second pre−purge in low speed.

3 − After the pre−purge is complete, a 20−second initial ig-

nitor warm−up period begins. The combustion air in­ducer continues to operate at low speed.

4 − After the 20−second warm−up period has ended, the gas

valve is energized on low fire (first stage) and ignition oc­curs. At the same time, the control module sends a sig­nal to begin an indoor blower 45−second ON−delay.
When the delay ends, the indoor blower motor is ener­gized on the low fire heating speed and the 24V hu­midifier terminal is energized. The furnace will contin­ue this operation as long as the thermostat has a
first−stage heating demand.

5 − If second−stage heat is required, the thermostat sec-

ond−stage heat contacts close and send a signal to the
integrated control. The integrated control initiates a
30−second second−stage recognition delay.

6 − At the end of the recognition delay, the integrated con-

trol energizes the combustion air inducer at high
speed. The control also checks the high−fire (second
stage) pressure switch to make sure it is closed. Once

Page 60

the the control receives a signal that the high−fire pres­sure switch is close, the high−fire (second stage) gas
valve is energized and the indoor blower motor is en­ergized for operation at the high−fire heating speed.

7 − When the demand for high−fire (second stage) heat is

satisfied, the combustion air inducer is switched to the
low−fire heating speed and the high−fire (second
stage) gas valve is de−energized. The low−fire (first
stage) gas valve continues operation. The indoor
blower motor is switched to the low−fire heating speed.

8 − When the thermostat demand for low−fire (first stage)

heat is satisfied, the gas valve is de−energized and the
field−selected indoor blower off delay begins. The
combustion air inducer begins a 5−second post−purge
period.

9 − When the combustion air post−purge period is com-

plete, the inducer and humidifier terminal are de−ener­gized. The indoor blower is de−energized at the end of
the off delay.

Applications Using A Single−Stage Thermostat

B − Heating Sequence −− Control Board Thermostat
Selection DIP switch in Single−Stage" Position

NOTE − In these applications, two−stage heat will be initi­ated by the integrated control if heating demand has not
been satisfied after the field adjustable period (10 or 15
minutes).

1 − On a call for heat, thermostat first−stage contacts close

sending a signal to the integrated control. The inte­grated control runs a self-diagnostic program and
checks high temperature limit switches for normally
closed contacts and pressure switches for normally
open contacts.The combustion air inducer is ener­gized at low speed and the 120 VAC humidifier termi­nal is energized.

2 − Once the control receives a signal that the low−fire

pressure switch has closed, the combustion air induc­er begins a 15−second pre−purge in low speed.

3 − After the pre−purge is complete, a 20−second initial ig-

nitor warm−up period begins. The combustion air in­ducer continues to operate at low speed.

4 − After the 20−second warm−up period has ended, the gas

valve is energized on low fire (first stage) and ignition oc­curs. At the same time, the control module sends a sig­nal to begin an indoor blower 45−second ON−delay.
When the delay ends, the indoor blower motor is ener­gized on the low−fire heating speed and the 24V hu­midifier terminal is energized. The integrated control
also initiates a second−stage on delay (factory−set at
10 minutes; adjustable to 15 minutes).

5 − If the heating demand continues beyond the second−

stage on delay, the integrated control energizes the
combustion air inducer at high speed. The control also
checks the high−fire (second stage) pressure switch to
make sure it is closed. Once the control receives a sig­nal the high−fire pressure switch is closed, the high−fire
(second stage) gas valve is energized and the indoor
blower motor is energized for operation at the high−fire
heating speed.

6 − When the thermostat heating demand is satisfied, the-

combustion air inducer begins a 5−second post−purge.
The field−selected indoor blower off delay begins.

7 − When the combustion air post−purge period is com-

plete, the inducer and humidifier terminal are de−ener­gized. The indoor blower is de−energized at the end of
the off delay.

Service

WARNING

ELECTRICAL SHOCK, FIRE,

OR EXPLOSION HAZARD.

Failure to follow safety warnings exactly could result
in dangerous operation, serious injury, death or
property damage.
Improper servicing could result in dangerous opera­tion, serious injury, death, or property damage.
Before servicing, disconnect all electrical power to
furnace.
When servicing controls, label all wires prior to dis­connecting. Take care to reconnect wires correctly.
Verify proper operation after servicing.

At the beginning of each heating season, system should be
checked as follows by a qualified service technician:

Blower

Check the blower wheel for debris and clean if necessary.
The blower motors are prelubricated for extended bearing
life. No further lubrication is needed.

WARNING

The blower access panel must be securely in place
when the blower and burners are operating. Gas
fumes, which could contain carbon monoxide, can
be drawn into living space resulting in personal inju­ry or death.

Filters

All G61MPV filters are installed external to the unit. Filters
should be inspected monthly. Clean or replace the filters
when necessary to ensure proper furnace operation.
Table 3 lists recommended filter sizes.

Exhaust and air intake pipes

Check the exhaust and air intake pipes and all connections
for tightness and to make sure there is no blockage.

NOTE − After any heavy snow, ice or frozen fog event the
furnace vent pipes may become restricted. Always check
the vent system and remove any snow or ice that may be
obstructing the plastic intake or exhaust pipes.

Electrical

1 − Check all wiring for loose connections.
2 − Check for the correct voltage at the furnace (furnace

operating).

3 − Check amp−draw on the blower motor.

Motor Nameplate__________Actual__________

Winterizing and Condensate Trap Care

1 − Turn off power to the unit.

Page 61

2 − Have a shallow pan ready to empty condensate water.

3 − Remove the drain plug from the condensate trap and

empty water. Inspect the trap then reinstall the drain
plug.

Cleaning Heat Exchanger

If cleaning the heat exchanger becomes necessary, follow
the below procedures and refer to figure 1 when disassem­bling unit. Use papers or protective covering in front of fur­nace while removing heat exchanger assembly.

1 − Turn off electrical and gas supplies to the furnace.

2 − Remove the upper and lower furnace access panels.

3 − Mark all gas valve wires and disconnect them from

valve.

4 − Remove gas supply line connected to gas valve. Re-

move gas valve/manifold assembly.

5 − Remove sensor wire from sensor. Disconnect 2-pin

plug from the ignitor.

6 − Disconnect wires from flame roll−out switches.

7 − Remove burner box cover and remove four burner box

screws at the vestibule panel and remove burner box.
Set burner box assembly aside.

NOTE − G61MPV−135 units are secured to the vesti­bule panel by two additional screws. These screws
must be removed for servicing; however it is not nec­essary to replace the screws.
NOTE − If necessary, clean burners at this time. Follow
procedures outlined in Burner Cleaning section.

8 − Loosen three clamps and remove flexible exhaust tee.

9 − Remove 3/8 inch rubber cap from condensate drain

plug and drain. Replace cap after draining.

10 − Disconnect condensate drain line from the conden-

sate trap. Remove condensate trap (it may be neces­sary to cut drain pipe). Remove screws that secure
condensate collars to either side of the furnace and re­move collars. Remove drain tubes from cold end
header collector box.

11 − Disconnect condensate drain tubing from flue collar.

Remove screws that secure both flue collars into
place. Remove flue collars. It may be necessary to cut
the exiting exhaust pipe for removal of the fittings.

12 − Mark and disconnect all combustion air pressure tub-

ing from cold end header collector box.

13 − Mark and remove wires from pressure switches. Re-

move pressure switches. Keep tubing attached to
pressure switches.

14 − Disconnect the 3-pin plug from the combustion air in-

ducer. Disconnect the two wires to the backup secon­dary limit, if applicable. Remove four screws which se­cure combustion air inducer to collector box. Remove
combustion air inducer assembly. Remove ground
wire from vest panel.

15 − Remove electrical junction box from the side of the fur-

nace.

16 − Mark and disconnect any remaining wiring to heating

compartment components. Disengage strain relief
bushing and pull wiring and bushing through the hole in

the blower deck.
17 − Remove the primary limit from the vestibule panel.
18 − Remove two screws from the front cabinet flange at

the blower deck. Spread cabinet sides slightly to allow

clearance for removal of heat exchanger.
19 − Remove screws along vestibule sides and bottom

which secure vestibule panel and heat exchanger as-

sembly to cabinet. Remove two screws from blower

rail which secure bottom heat exchanger flange. Re-

move heat exchanger from furnace cabinet.
20 − Back wash heat exchanger with soapy water solution

or steam. If steam is used it must be below 275°F

(135°C) .

21 − Thoroughly rinse and drain the heat exchanger. Soap

solutions can be corrosive. Take care to rinse entire

assembly.
22 − Reinstall heat exchanger into cabinet making sure that

the clamshells of the heat exchanger assembly are

resting on the support located at the rear of the cabi-

net. Remove the indoor blower to view this area

through the blower opening.
23 − Re-secure the supporting screws along the vestibule

sides and bottom to the cabinet.
24 − Reinstall cabinet screws on front flange at blower

deck.
25 − Reinstall the primary limit on the vestibule panel.
26 − Route heating component wiring through hole in blow-

er deck and reinsert strain relief bushing.
27 − Reinstall electrical junction box.
28 − Reinstall the combustion air inducer. Reconnect the

3−pin plug to the wire harness. Reconnect the two

wires to the backup secondary limit, if applicable.
29 − Reinstall pressure switches and reconnect pressure

switch wiring.
30 − Carefully connect combustion air pressure switch

hosing from pressure switches to proper stubs on

cold end header collector box.
31 − Reinstall condensate collars on each side of the fur-

nace. Reconnect drain tubing to collector box.
32 − Reinstall condensate trap on same side as exhaust

pipe. Reconnect condensate drain line to the conden-

sate trap.
33 − Use securing screws to reinstall flue collars to either

side of the furnace. Reconnect exhaust piping and ex-

haust drain tubing.
34 − Replace flexible exhaust tee on combustion air induc-

er and flue collars. Secure using three existing hose

clamps.
35 − Reinstall burner box assembly in vestibule area.
36 − Reconnect flame roll−out switch wires.
37 − Reconnect sensor wire and reconnect 2−pin plug from

ignitor.

Page 62

38 − Secure burner box assembly to vestibule panel using

four existing screws. Make sure burners line up in

center of burner ports.

39 − Reinstall gas valve manifold assembly. Reconnect

gas supply line to gas valve.
40 − Reinstall burner box cover.
41 − Reconnect wires to gas valve.
42 − Replace the blower compartment access panel.
43 − Refer to instruction on verifying gas and electrical con-

nections when re−establishing supplies.
44 − Follow lighting instructions to light and operate fur-

nace for 5 minutes to ensure that heat exchanger is

clean and dry and that furnace is operating properly.
45 − Replace heating compartment access panel.

Cleaning the Burner Assembly

1 − Turn off electrical and gas power supplies to furnace.

Remove upper and lower furnace access panels.
2 − Mark all gas valve wires and disconnect them from the

valve.
3 − Disconnect the gas supply line from the gas valve. Re-

move gas valve/manifold assembly.
4 − Mark and disconnect sensor wire from the sensor. Dis-

connect 2-pin plug from the ignitor at the burner box.
5 − Remove burner box cover and remove four screws

which secure burner box assembly to vest panel. Re-

move burner box from the unit.

NOTE − G61MPV−135 units are secured to the vesti-

bule panel by two additional screws. These screws

must be removed for servicing; however it is not nec-

essary to replace the screws.

6 − Use the soft brush attachment on a vacuum cleaner to

gently clean the face of the burners. Visually inspect

the inside of the burners and crossovers for any block-

age caused by foreign matter. Remove any blockage.
7 − Reconnect the sensor wire and reconnect the 2−pin

plug to the ignitor wiring harness.
8 − Reinstall the burner box assembly using the existing

four screws. Make sure that the burners line up in the

center of the burner ports.
9 − Reinstall the gas valve manifold assembly. Reconnect

the gas supply line to the gas valve. Reinstall the burn-

er box cover.
10 − Reconnect the gas valve wires to the gas valve.
11 − Replace the blower compartment access panel.
12 − Refer to instruction on verifying gas and electrical con-

nections when re−establishing supplies.

13 − Follow lighting instructions to light and operate fur-

nace for 5 minutes to ensure that heat exchanger is
clean and dry and that furnace is operating properly.

14 − Replace heating compartment access panel.

Planned Service

A service technician should check the following items dur­ing an annual inspection. Power to the unit must be shut off
for safety.

Fresh air grilles and louvers (on the unit and in the room
where the furnace is installed) − Must be open and unob­structed to provide combustion air.

Burners − Must be inspected for rust, dirt, or signs of water.

Vent pipe − Must be inspected for signs of water, damaged,

cracked or sagging pipe, or disconnected joints.

Unit appearance − Must be inspected for rust, dirt, signs
of water, burnt or damaged wires, or components.

Blower access door − Must be properly in place and pro­vide a seal between the return air and the room where the
furnace is installed.

Return air duct − Must be properly attached and provide
an air seal to the unit.

Operating performance − Unit must be observed during
operation to monitor proper performance of the unit and the
vent system.

Combustion gases − Flue products must be analyzed and
compared to the unit specifications.

Problems detected during the inspection may make it nec­essary to temporarily shut down the furnace until the items
can be repaired or replaced.

Instruct the homeowners to pay attention to their
furnace. Situations can arise between annual furnace in-

spections that may result in unsafe operation. For instance,
items innocently stored next to the furnace may obstruct
the combustion air supply. This could cause incomplete
combustion and the production of carbon monoxide gas.

Page 63

Ignition Control Board Diagnostic Codes (Red LED)

FLASH CODE

(X + Y)

STATUS / ERROR DESCRIPTION

FLASH CODE DESCRIPTIONS

Pulse A 1/4 second flash followed by four seconds of off time.

Heartbeat Constant 1/2 second bright and 1/2 second dim cycles.

X + Y

LED flashes X times at 2Hz, remains off for two seconds, flashes Y times at 2Hz, remains off for four
seconds, then repeats.

Pulse Power on − Standby.

Heartbeat Normal operation − signaled when heating demand initiated at thermostat.

FLAME CODES

1 + 2 Low flame current −− run mode.

1 + 3 Flame sensed out of sequence −− flame still present.

PRESSURE SWITCH CODES

2 + 3 Low pressure switch failed open.

2 + 4 Low pressure switch failed closed.

2 + 5 High pressure switch failed open.

2 + 6 High pressure switch failed closed.

2 + 7 Low pressure switch opened during ignition trial or heating demand.

LIMIT CODE

3 + 1 Limit switch open.

WATCHGUARD CODES

4 + 1 Watchguard −− Exceeded maximum number of retries.

4 + 2 Watchguard −− Exceeded maximum number of retries or last retry was due to pressure switch opening.

4 + 3 Watchguard −− Exceeded maximum number of retries or last retry was due to flame failure.

4 + 5 Watchguard −− Limit remained open longer than three minutes.

4 + 6

Watchguard −− Flame sensed out of sequence; flame signal gone.

4 + 7 Ignitor circuit fault −− Failed ignitor or triggering circuitry.

4 + 8 Low line voltage.

HARD LOCKOUT CODES

5 + 1 Hard lockout −− Rollout circuit open or previously opened.

5 + 2 Control failed self check, internal error (control will restart if error recovers).

5 + 3 No Earth ground (control will restart if error recovers).

5 + 4 Reversed line voltage polarity (control will restart if the error recovers).

5 + 6 Low secondary (24VAC) voltage.

Page 64

Troubleshooting: Heating Sequence of Operation

HEATING SEQUENCE OF OPERATION

NORMAL AND ABNORMAL HEATING MODE

CONTROL SELF−CHECK OKAY?

YES

GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.

INDOOR BLOWER OFF. (RESET CONTROL BY

TURNING MAIN POWER OFF.)

NO

POLARITY REVERSED.

STATUS ERROR CODE 5 + 4.

POWER ON

POLARITY OKAY?

SIGNAL HOLDS UNTIL UNIT IS PROPERLY GROUNDED.

STATUS ERROR CODE 5 + 3.

IS THERE A

PROPER GROUND?

NO

YES

A

NORMAL OPERATION:

STATUS LED −− PULSE

B

THERMOSTAT CALLS FOR HEAT:

STATUS LED −− HEARTBEAT

YES

PRIMARY AND SECONDARY LIMIT

SWITCHES CLOSED?

YES

NO

COMBUSTION AIR INDUCER OFF.

INDOOR BLOWER ON. HAS PRIMARY OR

SECONDARY LIMIT RESET WITHIN 3 MINUTES?

STATUS ERROR CODE 3 + 1.

ROLLOUT SWITCH CLOSED?

GAS VALVE OFF. COMBUSTION AIR INDUCER ON.

INDOOR BLOWER ON.

STATUS ERROR CODE 5 + 1.
SEQUENCE HOLDS UNTIL ROLLOUT SWITCH IS
RESET AND MAIN POWER IS INTERRUPTED OR

T’STAT IS CYCLED OFF/ON FOR 3 SEC. MINIMUM.

NO

YES

FIRST (LOW) STAGE PRESSURE SWITCH

CONTACTS OPEN?

NO

GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.

INDOOR BLOWER OFF. CONTROL REMAINS UNTIL

PRESSURE SWITCH IS DETECTED OPEN.

STATUS ERROR CODE 2 + 4

YES

GAS VALVE OFF.

COMBUSTION AIR INDUCER OFF.

INDOOR BLOWER OFF.

CONTROL WILL NOT ATTEMPT SECOND−STAGE

OPERATION DURING THIS HEAT DEMAND.

FIRST−STAGE OPERATION WILL BE ATTEMPTED.

STATUS ERROR CODE 2 + 6.

NO

TWO−STAGE OR SINGLE−STAGE THERMOSTAT

CALL FOR HEAT

COMBUSTION AIR INDUCER ON LOW SPEED.

STATUS LED −− HEARTBEAT

CONTINUED ON NEXT PAGE

NO

NO

60−MINUTE LIMIT WATCHGUARD MODE.

GAS VALVE OFF, COMBUSTION AIR INDUCER

OFF, INDOOR BLOWER OFF WITH DELAY.

STATUS ERROR CODE 4 + 5.

YES

NO

YES

SECOND (HIGH) STAGE PRESSURE SWITCH

CONTACTS OPEN?

NO

YES

Page 65

Troubleshooting: Heating Sequence of Operation (Continued)

HEATING SEQUENCE OF OPERATION

FIRST−STAGE (LOW FIRE) PRESSURE

SWITCH CLOSED WITHIN 2.5 MINUTES?

GAS VALVE OFF. COMBUSTION AIR INDUCER

OFF. INDOOR BLOWER OFF. UNIT WILL RETRY

AFTER 5−MINUTE WAIT PERIOD.

STATUS ERROR CODE 2 + 3.

YES

NO

15−SECOND COMBUSTION AIR INDUCER

PRE−PURGE INITIATED BY CLOSED FIRST−STAGE

PRESSURE SWITCH (or 15 SECOND

INTER−PURGE PERIOD.)

STATUS LED −− HEARTBEAT.

IGNITOR WARM−UP (20 SECONDS)

STATUS LED −− HEARTBEAT.

IS VOLTAGE ABOVE 90 VOLTS?

NO

COMBUSTION AIR INDUCER OFF, IGNITER OFF.

SIGNAL HOLDS UNTIL VOLTAGE RISES ABOVE 95

VOLTS. STATUS ERROR CODE 4 + 8.

YES

NO

COMBUSTION AIR INDUCER OFF, IGNITOR OFF.

SIGNAL HOLDS UNTIL IGNITOR IS REPLACED OR

RECONNECTED.

STATUS ERROR CODE 4 + 7.

YES

AT END OF IGNITOR 20 SECOND WARM UP

PERIOD, 4−SECOND TRIAL FOR IGNITION.

GAS VALVE OPENS, IGNITOR ENERGIZED DURING

4−SECOND TRIAL UNTIL FLAME SENSED.

YES

4−SECOND FLAME STABILIZATION PERIOD.

FLAME RECTIFICATION CURRENT CHECK

CAN FLAME BE PROVEN WITHIN 4

SECONDS AFTER GAS VALVE OPENS?

(u0.20 microamps)

GAS VALVE OFF. COMBUSTION AIR

INDUCER ON. INDOOR BLOWER OFF.

STATUS LED −− HEARTBEAT.

HAS CONTROL FAILED TO SENSE

FLAME FOR FIVE CONSECUTIVE TRIES

DURING A SINGLE HEAT DEMAND?

YES

THERMOSTAT CALLS FOR HEAT

STATUS LED − HEARTBEAT

(Refer to box A on previous page)

YES

FLAME PRESENT?

NO

HAS CONTROL RESET IGNITION SEQUENCE

FOUR (4) TIMES?

WATCHGUARD MODE.

STATUS ERROR CODE 4 + 3.

YES

CONTINUED ON NEXT PAGE

YES

NO

NO

CONTINUED

IS IGNITOR INTACT AND CONNECTED?

WATCHGUARD MODE. GAS VALVE OFF,

COMBUSTION AIR INDUCER OFF.

INDOOR BLOWER OFF.

STATUS ERROR CODE 4 + 1.

IS 60−MINUTE RESET PERIOD COMPLETE?

NO

YES

Page 66

Troubleshooting: Heating Sequence of Operation (Continued)

HEATING SEQUENCE OF OPERATION

LOW FLAME SIGNAL

(Does not affect control operation)

STATUS ERROR CODE 1 + 2.

FLAME SIGNAL ABOVE

(u1.40 microamps)

NO

YES

CONTINUED ON NEXT PAGE

YES

SINGLE−STAGE THERMOSTAT MODE

(DIP SWITCH SET AT SINGLE")

TWO STAGE THERMOSTAT MODE

(DIP SWITCH SET AT TWO")

YES

YES

START SECOND−STAGE RECOGNITION

ON DELAY (10 OR 15 MINUTES).

STATUS LED −− HEARTBEAT

45−SECOND INDOOR BLOWER ON DELAY BEGINS.

STATUS LED −− HEARTBEAT.

YES

YES

PRIMARY & SECONDARY LIMIT SWITCHES

CLOSED?

GAS VALVE OFF, COMBUSTION AIR INDUCER OFF,

INDOOR BLOWER ON.

STATUS ERROR CODE 3 + 1.

HAS PRIMARY OR SECONDARY LIMIT

SWITCH CLOSED WITHIN 3 MINUTES?

(Indoor blower on low speed during 3−minute period)

FIRST−STAGE (LOW FIRE)

PRESSURE SWITCH CLOSED?

LIMIT SWITCH WATCHGUARD MODE.

GAS VALVE OFF, COMBUSTION AIR INDUCER OFF,

INDOOR BLOWER OFF WITH DELAY.

STATUS ERROR CODE 4 + 5

IS 60−MINUTE RESET PERIOD COMPLETE?

THERMOSTAT CALLS FOR HEAT.

STATUS LED −− HEARTBEAT.

SEE BOX A.

NO

YES

GAS VALVE OFF. COMBUSTION AIR INDUCER ON.

INDOOR BLOWER OFF AFTER DELAY.

STATUS ERROR CODE 2 + 3. CONTROL RESTARTS

IGNITION SEQUENCE IF PRESSURE SWITCH

CLOSES WITHIN 2−1/2 MINUTES.

NO

YES

FIRST−STAGE HEAT DEMAND SATISFIED?

GAS VALVE OFF, COMBUSTION AIR INDUCER

OFF FOLLOWING POST PURGE.

INDOOR BLOWER OFF WITH DELAY

STATUS LED −− PULSE

YES

SECOND−STAGE HEAT DEMAND.

SECOND−STAGE HEAT DEMAND REQUIRED?

NO

SECOND STAGE PRESSURE SWITCH CLOSED?

ABNORMAL FLASH CODE.

NOTE − IF SECOND−STAGE PRESSURE SWITCH

WAS ORIGINALLY FOUND CLOSED,

ABNORMAL CODE WILL FLASH.

SECOND−STAGE PRESSURE SWITCH CLOSED

AT BEGINNING OF HEAT DEMAND?

STATUS ERROR CODE 2 + 6.

YES

NO

SECOND−STAGE 30−SECOND DELAY ON BEGINS.

STATUS LED −− HEARTBEAT.

SECOND−STAGE COMBUSTION AIR INDUCER

ON. SECOND−STAGE GAS VALVE ON. HIGH

HEAT INDOOR BLOWER SPEED ON.

STATUS LED −− HEARTBEAT.

YES

SECOND−STAGE PRESSURE SWITCH CLOSED

IN LESS THAN TEN (10) SECONDS?

STATUS LED −− HEARTBEAT

YES

NO

RETURNS TO FIRST−STAGE HEAT MODE WHICH
CONTINUES UNTIL SECOND−STAGE PRESSURE

SWITCH CAN BE PROVEN or HEAT DEMAND IS

SATISFIED. FIVE (5) MINUTE WAIT PERIOD

INITIATED BEFORE RETRY. WERE 5 ATTEMPTS

MADE FOR SECOND−STAGE HEAT?

YES

CONTINUES FIRST−STAGE HEATING DEMAND.

WILL NOT REATTEMPT SECOND−STAGE

HEATING DEMAND.

STATUS ERROR CODE 2 + 5.

SECOND STAGE HEAT DEMAND

STATUS LED −− HEARTBEAT.

NO

YES

NO

YES

CONTINUED

GAS VALVE OFF. COMBUSTION AIR INDUCER ON.

INDOOR BLOWER ON.

STATUS ERROR CODE 5 + 1. SEQUENCE HOLDS

UNTIL ROLLOUT SWITCH IS RESET AND MAIN

POWER IS INTERRUPTED OR THERMOSTAT

IS CYCLED OFF/ON FOR 3 SECOND MINIMUM.

ROLLOUT SWITCHES CLOSED?

NO

YES

YES

NO

YES

YES

Page 67

Troubleshooting: Heating Sequence of Operation (Continued)

HEATING SEQUENCE OF OPERATION

SEE BOX B

THERMOSTAT CALLS FOR HEAT.

SEE BOX A

NORMAL OPERATION.

YES

NO

RETURN TO FIRST−STAGE HEAT MODE.

FIRST−STAGE CONTINUES UNTIL SECOND−

STAGE PRESSURE SWITCH CAN BE PROVEN

or HEAT DEMAND IS SATISFIED. A FIVE (5)

MINUTE WAIT PERIOD IS INITIATED BEFORE

RETRY. WERE 5 ATTEMPTS MADE FOR

SECOND−STAGE HEAT?

YES

NO

SEE BOX C

FIRST−STAGE HEAT DEMAND SATISFIED?

HEAT DEMAND SATISFIED?

STATUS LED −− HEARTBEAT.

YES

TWO STAGE THERMOSTAT MODE?

(DIP SWITCH SET AT TWO")

SINGLE−STAGE THERMOSTAT MODE

(DIP SWITCH SET AT SINGLE")

YES

YES

FIRST AND SECOND STAGE HEAT

DEMAND SATISFIED SIMULTANEOUSLY.

STATUS LED −− HEARTBEAT.

YES

GAS VALVE OFF, COMBUSTION AIR

INDUCER OFF AFTER 5−SECOND

LOW SPEED POST PURGE PERIOD,

INDOOR BLOWER OFF DELAY

INITIATED ON LOW HEAT SPEED.

STATUS LED −− HEARTBEAT.

DEMAND FOR HEAT SATISFIED.

POWER ON STAND BY.

STATUS LED −− PULSE.

YES

SECOND STAGE HEAT

DEMAND SATISFIED?

STATUS LED −− HEARTBEAT.

NO

GAS VALVE, COMBUSTION AIR INDUCER

AND INDOOR BLOWER RETURN TO FIRST−

STAGE OPERATION.

STATUS LED −− HEARTBEAT.

YES

FIRST STAGE HEAT DEMAND SATISFIED?

YES

GAS VALVE OFF. COMBUSTION AIR INDUCER

OFF AFTER 5−SECOND LOW SPEED POST−

PURGE PERIOD. INDOOR BLOWER OFF.
DELAY INITIATED ON LOW HEAT SPEED.

STATUS LED −− PULSE.

CONTINUED

SECOND−STAGE (HIGH FIRE) HEAT

PRESSURE SWITCH CLOSED?

Page 68

Troubleshooting: Cooling Sequence of Operation

COOLING SEQUENCE OF OPERATION

SIGNAL POLARITY REVERSED.

CONTROL WILL CONTINUE TO CALL FOR COOLING

IN THIS CONDITION.

STATUS ERROR CODE 5 + 4.

POWER ON

YES

IS POLARITY REVERSED?

THERMOSTAT CALLS FOR FIRST−STAGE COOL.

COMPRESSOR AND CONDENSER FAN

ENERGIZED.

NO

IS THERE

PROPER GROUND?

YES

NO

INDOOR BLOWER ENERGIZED ON FIRST STAGE

COOL SPEED AFTER 2 SECOND DELAY.

FIRST−STAGE DEMAND FOR COOL SATISFIED?

NO

THERMOSTAT CALLS FOR SECOND−STAGE COOL.

COMPRESSOR AND CONDENSER FAN DE−ENERGIZED.

INDOOR BLOWER DE−ENERGIZED AFTER 45−SECOND

DELAY..

YES

INDOOR BLOWER RAMPS UP TO SECOND−STAGE COOL SPEED.

SECOND−STAGE DEMAND FOR COOL SATISFIED?

YES

UNIT RETURNS TO FIRST STAGE COOL

SIGNAL IMPROPER GROUND AT LED.

CONTROL WILL CONTINUE TO CALL FOR COOLING

IN THIS CONDITION.

STATUS ERROR CODE 5 + 3.

Page 69

Troubleshooting: Continuous Fan Sequence of Operation

CONTINUOUS LOW SPEED FAN SEQUENCE OF OPERATION

MANUAL FAN SELECTION MADE AT THERMOSTAT.

AFTER 2 SECOND DELAY, INDOOR BLOWER IS

ENERGIZED ON CONTINUOUS FAN SPEED.

THERMOSTAT CALLS FOR FIRST−STAGE HEAT.THERMOSTAT CALLS FOR FIRST STAGE COOL.

YES

YES

AFTER 45−SECOND DELAY, INDOOR BLOWER

SWITCHES TO LOW HEAT SPEED.

FIRST−STAGE HEAT DEMAND SATISFIED.

YES

NO

THERMOSTAT CALLS FOR SECOND−STAGE HEAT.

YES

INDOOR BLOWER SWITCHES TO HIGH HEAT SPEED

AFTER 30−SECOND RECOGNITION PERIOD.

SECOND−STAGE HEAT DEMAND SATISFIED.

YES

YES

INDOOR BLOWER RAMPS DOWN TO LOW

HEAT SPEED.

INDOOR BLOWER RAMPS TO FIRST STAGE

COOLING SPEED AFTER A 2−SECOND DELAY.

FIRST−STAGE COOL DEMAND SATISFIED?

YES

NO

SECOND STAGE COOL DEMAND SATISFIED?

INDOOR BLOWER RAMPS TO SECOND

STAGE COOL SPEED

YES

SECOND STAGE COOL DEMAND

INDOOR BLOWER RAMPS DOWN TO FIRST STAGE

COOL SPEED.

YES YES

Repair Parts List

The following repair parts are available through Lennox dealers. When ordering parts, include the complete furnace model
number listed on the CSA nameplate −− Example: G61MPV−36B−070−7. All service must be performed by a licensed

professional installer (or equivalent), service agency, or gas supplier.

Cabinet Parts

Upper access panel
Blower access panel
Top Cap

Control Panel Parts

Transformer
Integrated control board
Door interlock switch
Circuit Breaker

Blower Parts

Blower wheel
Motor
Motor mounting frame
Power choke (1 hp only)
Blower housing cutoff plate

Heating Parts

Flame Sensor

Heat exchanger assembly
Gas manifold
Combustion air inducer
Gas valve
Main burner cluster
Main burner orifices
Pressure switches
Ignitor
Primary limit control
Secondary limit control
Flame rollout switches
Combustion air inducer auxiliary limit

Page 70

Vent Pipe Sizing Worksheet

Proposed vent pipe size : ______

Termination kit catalog number : _____________
Vent pipe equivalency value from table 5 : ______

Total number of 90° elbows required (indoors and outdoors)
______ X 5 = ______ equivalent feet of pipe

Total number of 45° elbows required (indoors and outdoors)
______ X 2.5 = ______ equivalent feet of pipe

Linear feet of straight pipe required : ______

Add equivalent feet of vent pipe listed in
steps 2 through 5.

Step 1

Step 2

Step 3

Step 4

Step 5

Step 6

If the total is equal to, or less than, the allowable maximum given in table 7, the proposed pipe size is acceptable. If the
total exceeds the maximum allowed vent pipe length, repeat the process above using the next larger diameter pipe until
an acceptable total is achieved.

NOTE − In Direct Vent systems, total the equivalent length of either the exhaust OR intake piping run, depending upon which
will be LONGER. Intake and exhaust pipe diameter must be the same size and must be terminated in the same pressure
zone. Intake and exhaust pipe should be roughly the same length.

Equivalent Feet

TOTAL

Page 71

G61MPV Start−Up & Performance Check List

w.c. − LP/Propane

Filter Clean & Secure?

Supply Voltage

Electrical Connections Tight?

Job Name

Job Location

Installer
Unit Model No.

Furnace Btu Input

Line Pressure

Job No.

City

City

Serial No.

Date

State

Technician

Flue Connections Tight?

Heating Section

Thermostat

Calibrated? Heat Anticipator Properly Set? Level?

Fuel Type: Natural Gas?

Blower Motor Amps

Blower Motor H.P.

Gas Piping Connections
Tight & Leak−Tested?

Proper Draft?

Vent Clear?

State

Temperature Rise

Fan Control Off Setting

Fan Control Setting
(45 Seconds Fixed On)

Regulator Pressure

w.c. − Nat.:

LP/Propane Gas?

Combustion Gas Tested?

CO

2

CO

Condensate Connections Tight?

Page 72

Requirements for Commonwealth of Massachusetts

Modifications to NFPA−54, Chapter 10

Revise NFPA−54 section 10.8.3 to add the following re­quirements:

For all side wall, horizontally vented, gas−fueled equipment
installed in every dwelling, building or structure used in
whole or in part for residential purposes, including those
owned or operated by the Commonwealth and where the
side wall exhaust vent termination is less than seven (7)
feet above the finished grade in the area of the venting, in­cluding but not limited to decks and porches, the following
requirements shall be satisfied:

1 − INSTALLATION OF CARBON MONOXIDE DETEC-

TORS. At the time of installation of the side wall, hori­zontally vented, gas−fueled equipment, the installing
plumber or gasfitter shall observe that a hard−wired
carbon monoxide detector with an alarm and battery
backup is installed on the floor level where the gas
equipment is to be installed. In addition, the installing
plumber or gasfitter shall observe that a battery−oper­ated or hard−wired carbon monoxide detector with an
alarm is installed on each additional level of the dwell­ing, building or structure served by the side wall, hori­zontally vented, gas−fueled equipment. It shall be the
responsibility of the property owner to secure the ser­vices of qualified licensed professionals for the instal­lation of hard−wired carbon monoxide detectors.

a − In the event that the side wall, horizontally vented,

gas−fueled equipment is installed in a crawl space
or an attic, the hard−wired carbon monoxide detec­tor with alarm and battery back−up may be installed
on the next adjacent floor level.

b − In the event that the requirements of this subdivi-

sion cannot be met at the time of completion of
installation, the owner shall have a period of thirty
(30) days to comply with the above requirements;
provided, however, that during said thirty (30) day
period, a battery−operated carbon monoxide detec­tor with an alarm shall be installed.

2 − APPROVED CARBON MONOXIDE DETECTORS.

Each carbon monoxide detector as required in accor­dance with the above provisions shall comply with
NFPA 720 and be ANSI/UL 2034 listed and IAS certi­fied.

3 − SIGNAGE. A metal or plastic identification plate shall

be permanently mounted to the exterior of the building
at a minimum height of eight (8) feet above grade di­rectly in line with the exhaust vent terminal for the hori­zontally vented, gas−fueled heating appliance or
equipment. The sign shall read, in print size no less
than one−half (1/2) inch in size, GAS VENT DIRECT­LY BELOW. KEEP CLEAR OF ALL OBSTRUC­TIONS."

4 − INSPECTION. The state or local gas inspector of the

side wall, horizontally vented, gas−fueled equipment
shall not approve the installation unless, upon inspec­tion, the inspector observes carbon monoxide detec­tors and signage installed in accordance with the pro­visions of 248 CMR 5.08(2)(a) 1 through 4.

EXEMPTIONS: The following equipment is exempt
from 24 CMR 5.08(2)(a) 1 through 4:

1 − The equipment listed in Chapter 10 entitled Equip-

ment Not Required to Be Vented" in the most current
edition of NFPA 54 as adopted by the Board; and

2 − Product Approved side wall, horizontally vented, gas−

fueled equipment installed in a room or structure sepa­rate from the dwelling, building or structure used in
whole or in part for residential purposes.

MANUFACTURER REQUIREMENTS −
GAS EQUIPMENT VENTING SYSTEM PROVIDED.

When the manufacturer of Product Approved side wall,
horizontally vented, gas−fueled equipment provides a vent­ing system design or venting system components with the
equipment, the instructions provided by the manufacturer
for installation of the equipment and the venting system
shall include:

1 − Detailed instructions for the installation of the venting

system design or the venting system components:
and

2 − A complete parts list for the venting system design or

venting system.

MANUFACTURER REQUIREMENTS −
GAS EQUIPMENT VENTING SYSTEM NOT PROVIDED.

When the manufacturer of Product Approved side wall,
horizontally vented, gas−fueled equipment does not pro­vide the parts for venting the flue gases, but identifies spe­cial venting systems," the following requirements shall be
satisfied by the manufacturer:

1 − The referenced special venting system" instructions

shall be included with the appliance or equipment
installation instructions; and

2 The special venting systems" shall be Product Ap-

proved by the Board, and the instructions for that sys­tem shall include a parts list and detailed installation
instructions.

A copy of all installation instructions for all Product
Approved side wall, horizontally vented, gas−fueled
equipment, all venting instructions, all parts lists for
venting instructions, and/or all venting design instruc­tions shall remain with the appliance or equipment at
the completion of the installation.